Fix .gitignore: stop tracking ignored files

backend/lib/openzeppelin-contracts/contracts/access/README.adoc

@@ -0,0 +1,27 @@
+= Access Control
+
+[.readme-notice]
+NOTE: This document is better viewed at https://docs.openzeppelin.com/contracts/api/access
+
+This directory provides ways to restrict who can access the functions of a contract or when they can do it.
+
+- {AccessControl} provides a general role based access control mechanism. Multiple hierarchical roles can be created and assigned each to multiple accounts.
+- {Ownable} is a simpler mechanism with a single owner "role" that can be assigned to a single account. This simpler mechanism can be useful for quick tests but projects with production concerns are likely to outgrow it.
+
+== Authorization
+
+{{Ownable}}
+
+{{Ownable2Step}}
+
+{{IAccessControl}}
+
+{{AccessControl}}
+
+{{AccessControlCrossChain}}
+
+{{IAccessControlEnumerable}}
+
+{{AccessControlEnumerable}}
+
+{{AccessControlDefaultAdminRules}}