Man page improvements

* Removed the AUTHORS section as recommended by man-pages(7),
  the conventions for writing Linux man pages.
* Change the secion name to the more commonly used "User Commands".
* Don't say "this man page might be out dated".
* Always use the current version number of compton as "man version" in
  the man pages.

Also bumped the project version in meson.build

Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>

man/meson.build

@@ -3,8 +3,10 @@ if get_option('build_docs')
 	a2x = find_program('a2x')
 	foreach m : mans
 		custom_target(m, output: [m], input: [m+'.asciidoc'],
-		              command: [a2x, '--format', 'manpage', '@INPUT@',
-		                        '-D', meson.current_build_dir()],
+		              command: [a2x, '-a',
+		                        'compton-version='+version,
+		                        '--format', 'manpage', '@INPUT@', '-D',
+		                        meson.current_build_dir()],
 		              install: true, install_dir: 'share/man/man1/')
 	endforeach
 endif