Added 'releaseFile' back to action to maintain backwards compatibility.

README.md

@@ -18,9 +18,14 @@ The service account json in plain text, provided via a secret, etc.
 
 **Required:** The package name, or Application Id, of the app you are uploading
 
-### `releaseFiles`
+### `releaseFile`
+**DEPRECATED:** Please switch to using `releaseFiles` as this will be removed in the future  
+The Android release file to upload (.apk or .aab) 
 
-**Required:** The Android release file(s) to upload (.apk or .aab). Multiple files are separated by ','.
+### `releaseFiles`
+**CAVEAT:** Either this or `releaseFile` are required  
+
+The Android release file(s) to upload (.apk or .aab). Multiple files are separated by ','.
 
 ### `releaseName`
 
@@ -29,14 +34,14 @@ The release name. Not required to be unique. If not set, the name is generated f
 ### `track`
 
 **Required:** The track in which you want to assign the uploaded app.  
-**Default:** `production`  
+**Default:** `production`   
 _Values:_ `alpha`, `beta`, `internal`, `production`, `internalsharing`
 
 ### `inAppUpdatePriority`
 
 In-app update priority of the release. All newly added APKs in the release will be considered at this priority. Can take values in the range [0, 5], with 5 the highest priority.
 
-**Default:** `0`
+**Default:** `0`  
 _Values:_ `[0, 5]`
 
 ### `userFraction`