feat: readme.md

Author: aix3

README.md

@@ -1,6 +1,6 @@
 # fileserver
 
-The `fileserver` can be used as a static file server to share your file to people and also can as a private file server to upload and download your private files.
+The `fileserver` can be used as a static file server to share your file and also can as a private file server to upload and download your private files.
 
 ## Features
 - Directory index
@@ -11,27 +11,43 @@ The `fileserver` can be used as a static file server to share your file to peopl
 - JSON API
 
 ## Usage
-### API
-1. Execute the following command will upload the `img.png` to the `image` directory on the file server and produces a file named `img.png`. If the `image` directory does not exist, it will be created.
-    ```bash
-    $ curl -T img.png http://localhost:8880/image/
-    $ # or
-    $ curl -F 'file=@img.png' http://localhost:8880/image/
-    ```
-
-2. Execute the following command will upload the `img.png` to the `image` directory on the file server and produces a file named `another.png`. If the `image` directory does not exist, it will be created.
-    ```bash
-    $ curl -T img.png http://localhost:8880/image/another.png
-    $ # or
-    $ curl -F 'file=@img.png' http://localhost:8880/image/another.png
-    ```
-
-### Web UI
-**Index**
-> ![Index](img/index.png)
-
-**Upload**
-> ![Upload](img/upload.png)
+### API usage
+**File upload - Using default file name**
+
+Following command will upload the `img.png` to the directory `/image/a/b/c/` on the file server and produces a file named `img.png`.
+ ```bash
+ $ curl -T img.png http://localhost:8880/image/a/b/c/
+ $ # or
+ $ curl -F 'file=@img.png' http://localhost:8880/image/a/b/c/
+ ```
+
+**File upload - Specify file name**
+
+Following command will upload the `img.png` to the directory `/image/a/b/c/` on the file server and produces a file named `another.png`.
+ ```bash
+ $ curl -T img.png http://localhost:8880/image/a/b/c/another.png
+ $ # or
+ $ curl -F 'file=@img.png' http://localhost:8880/image/a/b/c/another.png
+ ```
+
+> Note: 
+> 1. If the specified directory does not exist on the file server, this directory will be created first.
+> 2. If the file to be uploaded already exists on the file server, the file will be overwritten.
+
+**File download**
+```bash
+$ curl http://localhost:8880/image/a/b/c/another.png
+```
+
+### UI usage
+**Directory index**
+
+The directory index access URL is the same as the API's access URL(Such as `http://localhost:8880/image/a/b/c/`). Just type the URL in the browser, and you'll see what's inside.
+
+> ![Index](_img/index.png)
+
+**File upload**
+> ![Upload](_img/upload.png)
 
 ## Build
 ```bash