[TASK] Rename administration section in documentation

Change-Id: I6d3a188633b5c4f4dba5e714a48499ef2389a810
Reviewed-on: https://review.typo3.org/25627
Reviewed-by: Nicole Cordes
Tested-by: Nicole Cordes
[TASK] Add old manual with link to rest documentation

Change-Id: If889472072d3cbba894dc04e7ea91861196b0679
Reviewed-on: https://review.typo3.org/25628
Reviewed-by: Nicole Cordes
Tested-by: Nicole Cordes