Update post "2020-11-26-installing-unsigned-extensions-permanently-to-firefox.md"

Mention the need for a Developer or ESR build of Firefox.

These steps either never worked or worked in 2020 but do no longer work. This commit clarifies that for the starry-eyed, hopeful Google Search travelers from the present and the future.

Author: TomasHubelbauer

_posts/2020-11-26-installing-unsigned-extensions-permanently-to-firefox.md

@@ -1,6 +1,6 @@
 ---
 layout: post
-title:  "Installing unsigned extensions permanently to Firefox"
+title:  "Installing unsigned extensions permanently to Firefox Developer edition"
 date:   2020-11-26 20:35:32 -0700
 categories: browser-extensions
 post_photo: assets/posts/install-unsigned-ext-firefox/post_photo.jpg
@@ -10,16 +10,21 @@ If you have worked with browser extension on Firefox, you likely go to `about:de
 
 Sometimes you may need to test how the extension behaves when Firefox starts, or, just want to leave your extension installed without signing it with the Developer Hub.
 
+**UPDATE 2023/Aug/11**: Unfortunately, this post seems obsolete now, while the approach worked in 2020, it does not work anymore for Firefox Release edition (the one most people use), you can see [Tomáš](https://github.com/TomasHubelbauer) research in a Github [thread](https://github.com/wiringbits/wiringbits.github.io/pull/38).
 
 ## Summary
 
-Gladly, there is a simple solution:
+Gladly, there is a simple solution if you are using Firefox Developer or the ESR build:
 1. Update your extension manifest to include custom `browser_specific_settings`.
 2. Disable signature checks while installing extensions.
 3. Package your extension as a zip file.
 4. Install the extension.
 5. Enable signature checks while installing extensions.
 
+Learn more at https://support.mozilla.org/en-US/kb/add-on-signing-in-firefox.
+
+**Note that it is not possible to configure `xpinstall.signatures.required` in Firefox Release!**
+These steps will not work for you if you are using the stable version of Firefox.
 
 ### Step 1
 Update your `manifest.json` to include a new key, the `id` could be any email: