docs(upload-release-asset): add documentation for upload-release-asset action

upload-release-asset/README.md

@@ -0,0 +1,23 @@
+# upload-release-asset
+
+The `upload-release-asset` action uploads a given file as an asset to a release.
+
+## Inputs
+
+### `file`
+
+The file that shall be uploaded.
+
+**Required:** yes
+
+### `name`
+
+The name of the release asset. If no name is specified, the file name is used.
+
+**Required:** false
+
+### `release`
+
+The ID of the release the asset shall be uploaded to.
+
+**Required:** true