[PR] [DOCS] Add ignore exclusion title
[PR] [DOCS] Add ignore exclusion title

Summary:
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I tend to link people to the ignore exclusions reference a lot. Providing a link instead of telling them to check bottom of the page is lot better.

Also update wording to be more accurate.

nmote

Pull Request resolved: https://github.com/facebook/flow/pull/8466

Reviewed By: samwgoldman

Differential Revision: D23373192

Pulled By: mroch

fbshipit-source-id: 109dfd71e49bbe8b205709a60fd82e4faf4f52f6

nmote/flow,nmote/flow,nmote/flow,nmote/flow,nmote/flow,nmote/flow,nmote/flow