docs: update target and source fields in README and action.yml descriptions

- Change in README.md: Updated required fields for `target` and `source`
- Change in action.yml: Updated description for `target` input field

Signed-off-by: Bo-Yi.Wu <appleboy.tw@gmail.com>

README.md

@@ -45,8 +45,8 @@ See the [action.yml](./action.yml) file for more detail information.
 * command_timeout - timeout for scp command, default is `10m`
 * key - content of ssh private key. ex raw content of ~/.ssh/id_rsa
 * key_path - path of ssh private key
-* target - target path on the server
-* source - scp file list
+* target - target path on the server, must be a directory (**required**)
+* source - scp file list (**required**)
 * rm - remove target folder before upload data, default is `false`
 * strip_components - remove the specified number of leading path elements.
 * overwrite - use `--overwrite` flag with tar, overwrite existing files when extracting

action.yml

@@ -29,7 +29,7 @@ inputs:
     description: 'include more ciphers with use_insecure_cipher'
     default: false
   target:
-    description: 'target path on the server'
+    description: 'target path on the server, must be a directory path.'
   source:
     description: 'scp file list'
   rm: