Add warning about provider not following OAuth2 spec

README.md

@@ -2,6 +2,9 @@
 
 A strategy to use and implement OAuth2 framework for authentication with federated services like Google, Facebook, GitHub, etc.
 
+> [!WARN]
+> This strategy expects the identity provider to strictly follow the OAuth2 specification. If the provider does not follow the specification and diverges from it, this strategy may not work as expected.
+
 ## Supported runtimes
 
 | Runtime    | Has Support |
@@ -86,7 +89,7 @@ authenticator.use(
 let tokens = await strategy.refreshToken(user.refreshToken);
 ```
 
-### Revoking tokens
+### Revoking Tokens
 
 You can revoke the access token the user has with the provider.