Fixed links in process_group_cpp_extension_tutorial.rst

[sekyondaMeta]

Removing mention of the Fully_Shared_Data_Parallel as it is a dead link=

Checklist

• The issue that is being fixed is referred in the description (see above "Fixes #ISSUE_NUMBER")
• Only one issue is addressed in this pull request
• Labels from the issue that this PR is fixing are added to this pull request
• No unnecessary issues are included into this pull request.

cc @svekars @brycebortree @AlannaBurke

[pytorch-bot]

🔗 Helpful Links

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• GLIBC not found in Nova workflows

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