Ignore all man sections as they are generated files.

Signed-off-by: NBrian Gernhardt <benji@silverinsanity.com>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

Documentation/.gitignore

 *.xml
 *.html
-*.1
-*.7
+*.[1-8]
 *.made
 howto-index.txt
 doc.dep