docs(codepipeline-actions): fix GithubSource oauthtoken link (aws#11584)

The previous link was redirecting to the root documentation page for CodePipeline. It looks like this was moved to an Appendix once Github actions v2 were added.

I also opened up a feature request to consider supporting v2 actions: aws#11582

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

packages/@aws-cdk/aws-codepipeline-actions/lib/github/source-action.ts

@@ -71,7 +71,7 @@ export interface GitHubSourceActionProps extends codepipeline.CommonActionProps
    * * **repo** - to read the repository
    * * **admin:repo_hook** - if you plan to use webhooks (true by default)
    *
-   * @see https://docs.aws.amazon.com/codepipeline/latest/userguide/GitHub-create-personal-token-CLI.html
+   * @see https://docs.aws.amazon.com/codepipeline/latest/userguide/appendix-github-oauth.html#GitHub-create-personal-token-CLI
    */
   readonly oauthToken: SecretValue;