adding how to link forked repo to a project board

[shades-7]

Why:

Closes #523

What's being changed:

Changed the content of the note and its position (https://docs.github.com/en/github/managing-your-work-on-github/linking-a-repository-to-a-project-board)

Check off the following:

• I have reviewed my changes in staging. (look for the deploy-to-heroku link in your pull request, then click View deployment)
• For content changes, I have reviewed the localization checklist
• For content changes, I have reviewed the Content style guide for GitHub Docs.

[welcome]

Thanks for opening this pull request! A GitHub docs team member should be by to give feedback soon. In the meantime, please check out the contributing guidelines.

[janiceilene]

Thanks so much for opening a PR with this fix @shades-7! I edited your original comment to read Closes https://github.com/github/docs/issues/523. When you write it that way, it automatically links the pull request to the issue (you can see it in the sidebar now!) and the issue will close once the PR is merged 🎉

I'll get this triaged for review 💖

[felicitymay]

👋🏻 Hi @shades-7

Thanks for your PR. It was really thoughtful of you to include a screenshot so that I could see how your changes looked (and good to see that you have managed to get the docs system working locally) ✨

For future reference, when you raise a PR, we automatically create a temporary server with your changes, as part of the testing. On the repository "Conversation" tab, there's a section called "This branch was successfully deployed" which contains a View deployment button to the staging environment. You can see your changes here: https://docs-3774--shades-7docs.herokuapp.com/en/github/managing-your-work-on-github/linking-a-repository-to-a-project-board.

I've added a comment with a change, but otherwise this looks good to merge.