docs/man/meson.build: Use -N for help2man to avoid texinfo section

If -N option is not added, the following section will be appended
to the generated man pages:

SEE ALSO
       The  full documentation for Timeshift is maintained as a Texinfo manual.  If the info and Timeshift programs are properly installed
       at your site, the command

              info Timeshift

       should give you access to the complete manual.

This is not desired, thus add the -N option to the help2man
invocation.

Signed-off-by: Boyuan Yang <byang@debian.org>

docs/man/meson.build

@@ -1,8 +1,8 @@
 help2man = find_program('help2man')
 
 mans = [
-  ['timeshift', [help2man, '--output=@OUTPUT@', timeshift]],
-  ['timeshift-gtk', [help2man, '--output=@OUTPUT@', timeshift_gtk]],
+  ['timeshift', [help2man, '-N', '--output=@OUTPUT@', timeshift]],
+  ['timeshift-gtk', [help2man, '-N', '--output=@OUTPUT@', timeshift_gtk]],
 ]
 
 foreach man: mans