Add docs and changelog

changelogs/unreleased/54826-use-read_repository-scope-on-read-only-files-endpoints.yml

+---
+title: Use read_repository scope on read-only files API
+merge_request:
+author:
+type: fixed

doc/api/repository_files.md

@@ -4,6 +4,18 @@
 
 **Create, read, update and delete repository files using this API**
 
+The different scopes available using [personal access tokens][personal-access-tokens] are depicted
+in the following table.
+
+| Scope | Description |
+| ----- | ----------- |
+| `read_repository` | Allows read-access to the repository files |
+| `api` | Allows read-write access to the repository files |
+
+> `read_repository` scope was [introduced](https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/23534) in GitLab 11.5.3.
+
+[personal-access-tokens]: (../user/profile/personal_access_tokens.md)
+
 ## Get file from repository
 
 Allows you to receive information about file in repository like name, size,