Bug 24484: Add explanatory text to batch patron deletion

Bug 24484: Add explanatory text to batch patron deletion

This patch adds a more detailed explanation about what the tool can do.

To test:

1) Open up the Batch patron deletion and anonymisation tool
2) Check the help text near the top of the screen
3) Install the patch and repeat steps 1 and 2
4) Check the help text has changed to the new version

Signed-off-by: Andrew Fuerste-Henry <andrew@bywatersolutions.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>