[FOLLOWUP] Restructure lowlevel commands and documentation

Convert the simple Markdown manual into a reStructuredText document
to stick to best practices for TYPO3 extensions.

Change-Id: Ibe50d8f404984c5c0c3abe1731a8c95322752e8f
Resolves: #67946
Releases: master
Reviewed-on: http://review.typo3.org/41010


Reviewed-by: Benjamin Mack <benni@typo3.org>
Tested-by: Benjamin Mack <benni@typo3.org>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Andreas Fernandez <typo3@scripting-base.de>
Tested-by: Andreas Fernandez <typo3@scripting-base.de>