improve README structure and installation instructions

README.md

@@ -8,30 +8,178 @@
 [![REUSE status](https://api.reuse.software/badge/github.com/LibreSign/libresign)](https://api.reuse.software/info/github.com/LibreSign/libresign)
 [![Start contributing](https://img.shields.io/github/issues/LibreSign/libresign/good%20first%20issue?color=7057ff&label=Contribute)](https://github.com/LibreSign/libresign/issues?q=is%3Aissue+is%3Aopen+sort%3Aupdated-desc+label%3A%22good+first+issue%22)
 
-Nextcloud app to sign PDF documents.
+# LibreSign for Nextcloud
 
-<img src="img/LibreSign.png" />
+LibreSign is a digital signature application for Nextcloud that enables secure document signing workflows directly within your self-hosted environment.
 
-[![Request a feature](https://img.shields.io/badge/Request%20a%20feature-7057ff?style=for-the-badge)](https://github.com/LibreSign/libresign/issues/new?template=feature_request.yml)
-[![Report a BUG](https://img.shields.io/badge/Report%20a%20bug-8e0000?style=for-the-badge)](https://github.com/LibreSign/libresign/issues/new?template=bug_report.yml)
+It supports internal and external signers, certificate-based signatures, and full document lifecycle management.
 
-## Star History
+## Why LibreSign?
 
-[![Star History Chart](https://api.star-history.com/svg?repos=libresign/libresign&type=Date)](https://www.star-history.com/#libresign/libresign&Date)
+- Fully self-hosted digital signature solution
+- Integrated with Nextcloud ecosystem
+- Supports internal and external signers
+- Open source (AGPL-3.0)
+- Extensible API
 
-## Contributing
+---
+## Quick Links
+
+- 📖 [Full Documentation](https://github.com/LibreSign/documentation)
+- 🐛 [Report a bug](https://github.com/LibreSign/libresign/issues/new?template=bug_report.yml)
+- 💡 [Request a feature](https://github.com/LibreSign/libresign/issues/new?template=feature_request.yml)
+- 🌍 [Translations (Transifex)](https://app.transifex.com/nextcloud/nextcloud/libresign)
+---
+
+## Who is this for?
+
+- 🛠 Nextcloud administrators who want to deploy a digital signature solution
+- 👤 End users who need to sign or request signatures on documents
+- 🏢 Organizations looking for a self-hosted signature workflow
+
+---
+
+## Documentation
+
+Complete guides are available for:
+
+- 🔧 Administrators (installation, configuration, certificates)
+- 👥 Users (how to request and sign documents)
+- 🧪 Developers (architecture and API)
+
+👉 https://github.com/LibreSign/documentation
+
+---
+
+## Installation
+
+LibreSign can be installed from the Nextcloud App Store or manually.
+
+After enabling the app, administrators must install required standalone dependencies and configure certificates.
+
+### 1️⃣ Install dependencies
+Run the following command as your web server user:
+`occ libresign:install --java --pdftk --jsignpdf`
+
+This will install:
+- Java (standalone JRE)
+- PDFtk
+- JSignPdf
+
+All binaries are installed inside the Nextcloud `data/appdata_*/libresign` directory.
+No system-wide installation is required.
+
+### 2️⃣ Verify installation
+`sudo -u www-data php /path/to/nextcloud/occ libresign:configure:check`
+
+This command verifies:
+- Java availability
+- PDFtk setup
+- JSignPdf setup
+- OpenSSL configuration
+- Certificate environment
+
+### 3️⃣ Configure root certificate
+You can generate a certificate using OpenSSL or CFSSL.
+
+Example using OpenSSL:
+`sudo -u www-data php /path/to/nextcloud/occ libresign:configure:openssl --cn="Your Organization - Digital Signature" --o="Your Organization" --c="FR" --st="Region" --l="City"`
+
+Certificates are generated and stored inside the Nextcloud data directory: `nextcloud_data_dir/appdata_*/libresign`
+
+No additional server-level configuration is required.
+
+📖 For full configuration details, advanced setups, and troubleshooting:
+https://github.com/LibreSign/documentation
+
+---
+
+## Architecture
+
+LibreSign installs all required binaries in standalone mode inside the Nextcloud data directory.
+This design improves portability and avoids dependency conflicts with the host system.
+
+It does not require:
+
+- System-wide Java installation
+- System-wide PDFtk installation
+- External certificate authority configuration
 
-There are many ways to contribute, including writing code, filing issues on GitHub, helping people Overflow, helping to triage, reproduce, or fix bugs that people have filed, adding to our documentation.
-To get more details go to our [contributing guide](CONTRIBUTING.md).
+All cryptographic operations are self-contained within Nextcloud.
+
+---
+
+## How it works
+
+1. A user uploads a document.
+2. The user defines signers (internal or external).
+3. Signers receive a notification or link.
+4. The document is signed and stored in Nextcloud.
+5. Signature validation and certificate verification are performed automatically.
+---
+
+## Requirements
+
+- PHP: Must meet the minimum version required by the supported Nextcloud version.
+- NodeJS: Required for development builds only.
+
+### Additional dependencies:
+- poppler-utils
+- System locale configured with UTF-8 charset
+
+---
 
 ## Integrations
 
 * [GLPI](https://github.com/LibreSign/libresign-glpi): Plugin to sign GLPI tickets
 * [Approval](https://github.com/nextcloud/approval): Approve/reject files based on workflows defined by admins
 
+---
+
 ## API Documentation
 
-[API Documentation](https://libresign.github.io/)
+Developer manual: https://docs.libresign.coop/developer_manual/index.html
+
+---
+
+## Security
+
+LibreSign uses certificate-based digital signatures and follows best practices for secure document validation. 
+
+For responsible disclosure and security policy, please see [SECURITY.md](SECURITY.md).
+
+---
+
+## Contributing
+
+We welcome contributions!
+
+- Bug reports and feature requests: Issues tab
+- Code contributions: Pull Requests
+- Translations: Transifex https://app.transifex.com/nextcloud/nextcloud/libresign
+- Documentation improvements: https://github.com/LibreSign/documentation
+- To get more details go to our [contributing guide](CONTRIBUTING.md).
+
+[![Request a feature](https://img.shields.io/badge/Request%20a%20feature-7057ff?style=for-the-badge)](https://github.com/LibreSign/libresign/issues/new?template=feature_request.yml)
+[![Report a BUG](https://img.shields.io/badge/Report%20a%20bug-8e0000?style=for-the-badge)](https://github.com/LibreSign/libresign/issues/new?template=bug_report.yml)
+
+---
+
+## License
+
+LibreSign (this repository) is licensed under the **GNU Affero General Public License v3.0 or later (AGPL-3.0-or-later)**.
+- 📂 All licenses: [LICENSES/](LICENSES/)
+- 📘 Also in Documentation repository: https://github.com/LibreSign/documentation/blob/main/LICENSE
+
+---
+
+## Screenshots
+
+<p align="center">
+  <img src="img/LibreSign.png" alt="LibreSign interface screenshot" width="900"/>
+</p>
+
+---
 
 ## Contributors ✨
 
@@ -40,3 +188,7 @@ Thanks go to these wonderful people:
 <a href="https://github.com/LibreSign/libresign/graphs/contributors">
   <img src="https://contrib.rocks/image?repo=LibreSign/libresign" />
 </a>
+
+## Star History
+
+[![Star History Chart](https://api.star-history.com/svg?repos=libresign/libresign&type=Date)](https://www.star-history.com/#libresign/libresign&Date)