[BUGFIX] Adjust comment for default HTTP-userAgent

The default userAgent is for example TYPO3/6.2.4

Change-Id: I2412b901a3a42938a433e7d8a414de24587011a3
Resolves: #60365
Releases: 6.3, 6.2
Reviewed-on: https://review.typo3.org/31641
Reviewed-by: Markus Klein <klein.t3@reelworx.at>
Tested-by: Markus Klein <klein.t3@reelworx.at>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Stefan Neufeind <typo3.neufeind@speedpartner.de>
Tested-by: Stefan Neufeind <typo3.neufeind@speedpartner.de>