[Docs] adding link to closure tags
[Docs] adding link to closure tags

This CL adds a direct link to the closure tags in the docs for Closure.  I'm new to Closure and I this was something I wanted a link to sooner.  Having a direct link here may help future-new-users.

BUG=

Review URL: https://codereview.chromium.org/1358903002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#350110}

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