Fix documentation related to tokens. The secrets.GITHUB_TOKEN provided by the GitHub Actions App can do everything related to the repo if we elevate its permissions, including calling workflow_dispatch and repository_dispatch.
Some people in my organization are using PAT's instead of the secrets.GITHUB_TOKEN when using this action because of this README suggestion, even when they are calling the same repository. Using PATs in that contexts provides unnecessary security risks.
Ran into an issue where I was using a user that did not have explicit access to the repo that I was trying to trigger an event for. I'm not sure if the user needs write access to the repo, but it seems logical to me that someone with `read` only access can not trigger GH actions.