Cleanup @mcp prompt markdown

[powerman]

Description

As discussed in #188 (comment) here are cleanups for @mcp prompt markdown.

This PR fixes all reasonable markdownlint issues in the prompt.

I've used many small commits fixing individual issues, so you can chery-pick them instead of merging the whole PR if you like to.

A couple of discussed changes are not included in the PR:

• Using JSON instead of Lua for Schema - I'm waiting for a response on feat(codecompanion): add format_action #188 (comment)
• Hiding info/example related to disabled servers and toggling them in case of auto_toggle_mcp_servers = false (this is kind of logic change and not really suitable for this "formatting change" PR)

Checklist

• I've read the contributing guidelines and have adhered to them in this PR
• I've updated the README and/or relevant docs pages
• I've run make test to ensure all tests pass
• I've run make format to format the code
• I've run make docs to update the vimdoc pages

[ravitemer]

Thank you @powerman for the PR. You have fixed many inconsistencies that might confuse the LLM.

Using JSON instead of Lua for Schema - I'm waiting for a response on

We have the utils.pretty_json function for formatting.