Added link to known limitations in SSH agent forwarding documentation (#7251)

Co-authored-by: Nick Trogh <1908215+ntrogh@users.noreply.github.com>
Co-authored-by: Brigit Murtaugh <brigit.murtaugh@microsoft.com>

remote/advancedcontainers/sharing-git-credentials.md

@@ -70,6 +70,8 @@ if [ -z "$SSH_AUTH_SOCK" ]; then
 fi
 ```
 
+If you encounter any issues, you may want to check the Dev Containers extension's [known limitations](/docs/devcontainers/containers.md#known-limitations).
+
 ## Sharing GPG Keys
 
 If you want to [GPG](https://www.gnupg.org/) sign your commits, you can share your local keys with your container as well. You can find out about signing using a GPG key in [GitHub's documentation](https://docs.github.com/authentication/managing-commit-signature-verification).