docs: update documentation Oct 2024

[philknows]

Motivation

Our documentation has been undergoing incremental improvements to remove old content, update for relevance and add new content that hasn't been documented yet. This is one PR in a series of future PRs to improve docs for better user/developer experiences.

Related to #5961

Description

This PR addresses the following in our documentation:

• Fixes footer and just links to pertinent communications/call to actions
• Removes old .md files which were empty or otherwise, not being actively developed on
• Removes Google site verification as we no longer use any Google type analytics
• Spelling/grammar updates
• Removes content relating to The Merge
• Updates specification for hardware minimums/recommendations
• Fixes broken links
• Sidebar navigation updated to better arrange/detail information
• Persist our quickstart custom setup guide into our documentation. Previously located at https://hackmd.io/@philknows/rJegZyH9q
• Include proposer config documentation

More to come in future updates that were not included.