docs: declare body_path input

action.yml

@@ -10,6 +10,9 @@ inputs:
   body:
     description: "Note-worthy description of changes in release"
     required: false
+  body_path:
+    description: "Path to load description of changes in this release"
+    required: false
   name:
     description: "Gives the release a custom name. Defaults to tag name"
     required: false