Clarify Permissions Calculation for Workflow Jobs in Documentation

[Vikranth3140]

Why:

Closes: Issue #32398

What's being changed (if available, include any code snippets, screenshots, or gifs):

The documentation for "Automatic Token Authentication" is updated to clarify that the read-only adjustment applies to all pull request-related events triggered on a fork PR except for the pull_request_target event.

Updated Section:

Finally, if the workflow was triggered by a pull request from a forked repository, and the Send write tokens to workflows from pull requests setting is not selected, the permissions are adjusted to change any write permissions to read-only, except for the pull_request_target event. This applies to all pull request-related events, including pull_request_review.

Check off the following:

• [x] I have reviewed my changes in staging, available via the View deployment link in this PR's timeline (this link will be available after opening the PR).
  • For content changes, you will also see an automatically generated comment with links directly to pages you've modified. The comment won't appear if your PR only edits files in the data directory.
• [x] For content changes, I have completed the self-review checklist.

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