Add text regarding including shared analysis options

[srawlins]

Fixes #6174.

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[srawlins]

CC @parlough @bwilkerson I'd love love love feedback, thanks!

[dart-github-bot]

Visit the preview URL for this PR (updated for commit 3ba8930):

https://dart-dev--pr6402-multiple-shares-1ytpqi9p.web.app

[bwilkerson]

I've added a couple of comments, but they're all just opinions, so do with them as you please.

[MaryaBelanger]

Thanks @srawlins! Some edits for clarity

[parlough]

Looks great to me once Marya's suggestions are applied.

Thanks so much for tackling the feature and these docs :D

[MaryaBelanger]

Thanks @srawlins! Some edits for clarity

Since these are all just grammar / wording, I'm going to commit them and merge the PR :) Thanks again Sam!

[srawlins]

Thanks a million, Marya!