Added option to plugin schema and documentation

Author: toote

README.md

@@ -73,6 +73,10 @@ Assuming the underlying executables are available, the allowed values are:
 * `tgz`: `tar` with gzip compression
 * `zip`: `(un)zip` compression
 
+### `force` (boolean, optional, save only)
+
+Force saving the cache even if it exists. Default: `false`.
+
 ### `manifest` (string, required if using `file` caching level)
 
 A path to a file or folder that will be hashed to create file-level caches.

plugin.yml

@@ -21,6 +21,8 @@ configuration:
         - zip
         - tar
         - tgz
+    force:
+      type: boolean
     manifest:
       type: string
     path: