DOC-7538: Mark channels as favorites page needs animated GIFs for mobile app workflows

[Rutam21]

Summary

This PR adds visual workflows for the Mattermost mobile app tab on the Mark channels as favorites page.

Ticket Link

Fixes #7538

• This PR follows Mattermost Contributing Guidelines.
• The changes are tested in a local docs build.

[mattermost-build]

Hello @Rutam21,

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[Rutam21]

@cwarnermm Please review and suggest changes, if any. Thanks.

@lindy65 Please add this to my queue for QA Testing, if needed. Thank you.

[lindy65]

Assigned to you for testing @Rutam21 👍

[github-actions]

Newest code from Rutam21 has been published to preview environment for Git SHA 4986779

[Rutam21]

The changes are tested in the preview environment and reflect properly.

• The Mark channels as favorites page now has respective workflow images under the mobile tab for visual learners.

Please take a look at the screenshots below for confirmation.

Current Docs Page [Mark channels as favorites]

Preview Environment Page Video

PR-7546QATesting.mp4

[ Awaiting final review from @cwarnermm ]

cc: @lindy65

[lindy65]

Thanks for testing @Rutam21 :)

[lindy65]

/update-branch

[cwarnermm]

Thanks, @Rutam21!