Add 'official' to readme

Author: kzu

readme.md

@@ -7,7 +7,7 @@
 [![Build](https://github.com/devlooped/CredentialManager/workflows/build/badge.svg?branch=main)](https://github.com/devlooped/CredentialManager/actions)
 
 <!-- #content -->
-Packages the [Git Credential Manager](https://github.com/git-ecosystem/git-credential-manager/) cross-platform credential store 
+Packages the official [Git Credential Manager](https://github.com/git-ecosystem/git-credential-manager/) cross-platform credential store 
 implementation supporting Windows, macOS and Linux for use as a NS2.0 library with no UI or external dependencies.
 
 Release version numbers track the [GCM releases](https://github.com/GitCredentialManager/git-credential-manager/releases) themselves.
@@ -21,7 +21,7 @@ using GitCredentialManager;
 ICredentialStore store = CredentialManager.Create("myapp");
 ```
 
-The namespace for the `CredentialManager` static factory class is the same as GCM itself 
+The namespace for the `CredentialManager` static factory class is the same as the official GCM itself 
 for convenience: `GitCredentialManager`.
 
 The optional *namespace* argument (`myapp` above) can be used to scope credential