chore: add information about the new signOut redirect url option

[Samaritan1011001]

Description of changes:

Adds two similar sections on using the new parameter on signOut API to both React Native and Web filters to the "Add social provider sign-in" section of the documentation. This change is to support the feature release in Amplify JS.

Related GitHub issue #, if available:

Instructions

If this PR should not be merged upon approval for any reason, please submit as a DRAFT

Which product(s) are affected by this PR (if applicable)?

• amplify-cli
• amplify-ui
• amplify-studio
• amplify-hosting
• amplify-libraries

Which platform(s) are affected by this PR (if applicable)?

• JS
• Swift
• Android
• Flutter
• React Native

Please add the product(s)/platform(s) affected to the PR title

Checks

• Does this PR conform to the styleguide?

• Does this PR include filetypes other than markdown or images? Please add or update unit tests accordingly.

• Are any files being deleted with this PR? If so, have the needed redirects been created?

• Are all links in MDX files using the MDX link syntax rather than HTML link syntax?
  
  ref: MDX: [link](https://docs.amplify.aws/)
  HTML: <a href="https://docs.amplify.aws/">link</a>

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[HuiSF]

Sanity check: Gen2 doc doesn't have an equivalent page for adding this information?

[Samaritan1011001]

I couldn't find any relevant place. Only relatable location is the signOut page but that's for the common use-case and Gen2 has nothing on signInWithRedirect I believe.

[Samaritan1011001]

Added it here for Gen2.

[jimblanc]

Few nits but looks good!

[israx]

I think we should move the proposed changes to the signOut section on gen2 docs. Eventually, gen1 docs will be deprecated, requiring us to make changes.

[israx]

I think this section is redundant. By examining lines 744 and 746, I interpret that the change we are currently implementing is the inclusion of multiple redirects, which was actually a feature offered by v6 upon its release.

[Samaritan1011001]

On RN page, we don't have any info on redirects so I thought this will set up some context before diving into multiple redirects.

[josefaidt]

left a few comments but overall we'll want to consolidate the snippets to a common pattern (ts, minimal usage examples), add a callout to the sign-out page for when to use this, and add a short explainer on when or why you'd want to use this feature