Ensure related commands are reconstructed correctly (all languages)

[sudojunior]

Reason for the change

• Before this change, the page.path was attempting to replace page.url with the *.md extension that doesn't exist.
• Along with the 88 file changes to bring method siblings in line with each other as much as possible.

Description - direct from #1303

The reason for the complex replacement join is due to how liquid identifies and handle strings (and also the order of execution)

• Actual: split, slice, join(/), append(/), append(related[1])
• Attempted: split, slice, append(related[1]), join(/) Placing append before a join breaks the sequence and turns the array of strings into a concatenated string before the join can run resulting in apijavascriptnext instead of api/javascript/next/

Code examples No core documentation was changed.

Checklist

• [x] I have read and agreed to the RethinkDB Contributor License Agreement

References

• Google Sheet created for this PR, to determine what needed to be changed without double backing on myself.

  Language navigator faults / Page mismatch also ended up being tracked on this spreadsheet despite saying they actively weren't.

Side notes

• Not all pages have the self-reference problem, which leads me to believe it's a problem with caching on the deployment end.
• span.disabled for language navigator no longer exists, and I cannot determine when it was removed or if it existed to begin with.

[srh]

Thank you for noticing the bug and making a PR for the fix. Merging.