[TASK] Fix typos & grammar issues in Install Tool

Change-Id: Iaad158d8e0a67ee839cfd346e33f9cf466620893
Resolves: #55098
Releases: 6.2
Reviewed-on: https://review.typo3.org/26896
Reviewed-by: Markus Klein
Tested-by: Markus Klein
Reviewed-by: Oliver Klee
Reviewed-by: Wouter Wolters
Tested-by: Wouter Wolters