docs: remove incorrect note about OAuth only in stdio

Remote server handles OAuth automatically via host app integration

Author: SamMorrowDrums

README.md

@@ -217,8 +217,6 @@ For stdio mode, you can use OAuth 2.1 instead of a Personal Access Token. The se
 
 See [docs/oauth-authentication.md](docs/oauth-authentication.md) for full setup instructions, including how to create a GitHub OAuth App.
 
-> **Note**: OAuth is only available in stdio mode. For remote server usage, use Personal Access Tokens.
-
 ### GitHub Enterprise Server and Enterprise Cloud with data residency (ghe.com)
 
 The flag `--gh-host` and the environment variable `GITHUB_HOST` can be used to set