[BUGFIX][t3editor] Description of new options compressJs and compressCss

Change-Id: Ie61a4415b0efd4bd624e88d908933bd4f9e9350c
Resolves: #31238
Releases: 4.6
Reviewed-on: http://review.typo3.org/6255
Reviewed-by: Xavier Perseguers
Tested-by: Xavier Perseguers
Reviewed-by: Stefan Galinski
Tested-by: Stefan Galinski