[Patch] Key help for gitk

Greetings,

 gitk has a few more key options than I was aware (font
increase/decrease for example). The following patch adds some details
to the 'About' dialog.
 (These need to be reviewed for sanity, as I can't work out how the
search keys are ment to work.)

 Paul Schulz

Paul Schulz, Sun, Apr 02, 2006 02:21:16 +0200:

+<Ctl-equal> - Incrument font size
+<Ctl-KP_Add> - Incrument font size

Typo: "IncrEment"