update allowed-update-types description

Author: tjenkinson

action.yml

@@ -9,7 +9,7 @@ inputs:
     required: true
     description: 'Comma separated list of usernames auto merge is allowed for'
   allowed-update-types:
-    description: 'Comma separated list of types of updates that are allowed. Supported: [devDependencies|dependencies]:[major|minor|patch]'
+    description: 'Comma separated list of types of updates that are allowed. Supported: [devDependencies|dependencies]:[major|minor|patch|premajor|preminor|prerelease]'
     default: 'devDependencies:minor, devDependencies:patch'
   approve:
     description: 'Automatically approve the PR if it qualifies for auto merge'