doc: Add statistics page for v2022.07

Our statistics pages have always been generated by gitdm.  After
patching gitdm to generate an acceptable Sphinx output for tables,
include that and some other basic formatting here.

Cc: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>