tools: bpftool: Include common options from separate file

Nearly all man pages for bpftool have the same common set of option
flags (--help, --version, --json, --pretty, --debug). The description is
duplicated across all the pages, which is more difficult to maintain if
the description of an option changes. It may also be confusing to sort
out what options are not "common" and should not be copied when creating
new manual pages.

Let's move the description for those common options to a separate file,
which is included with a RST directive when generating the man pages.

Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200909162500.17010-3-quentin@isovalent.com

tools/bpf/bpftool/Documentation/bpftool-net.rst

@@ -75,22 +75,7 @@ DESCRIPTION
 
 OPTIONS
 =======
-	-h, --help
-		  Print short generic help message (similar to **bpftool help**).
-
-	-V, --version
-		  Print version number (similar to **bpftool version**).
-
-	-j, --json
-		  Generate JSON output. For commands that cannot produce JSON, this
-		  option has no effect.
-
-	-p, --pretty
-		  Generate human-readable JSON output. Implies **-j**.
-
-	-d, --debug
-		  Print all logs available from libbpf, including debug-level
-		  information.
+	.. include:: common_options.rst
 
 EXAMPLES
 ========