docs: fix markdown lint issues and typos in README

[alwynpan]

Summary

Cleans up the README's markdown and fixes documentation typos.

Markdown lint

• Blank lines around headings/tables, consistent emphasis style, removed multiple blank lines.
• Converted indented code blocks to fenced blocks and added languages (text/bash/json).
• Fixed a broken in-doc link (#data-volumes → #persistent-storage) and two MSSQL tables missing a trailing _FILE cell.
• Re-aligned affected table rows so pipes stay consistent.

Typos

• seperating/Seperate → separating/Separate
• BACKUP_LOCTION → BACKUP_LOCATION
• executed.See → executed. See, targed → target, the a cleanup → a cleanup
• doubled "files files", stray :., unclosed parens, #4= → $4=, syntax/ → syntax:, and a malformed backtick.