[TASK] Documentation to reST

Move documentation to reStructuredText.

Resolves: #63127
Releases: 1.8
Change-Id: I1dc19455bd4da82a46175b214824666f0bcf59e5
Reviewed-on: http://review.typo3.org/34442
Reviewed-by: Francois Suter <francois@typo3.org>
Tested-by: Francois Suter <francois@typo3.org>