docs: add documentation for zotonic_dispatch_path_rewrite var

(cherry picked from commit 095adac2d573d48e186d701a553d62a46f2d1f87)
mod_geomap: Move module to own repository

This reduces the download footprint for Zotonic quite a bit. mod_geomap
is not used on every site and is considered quite a specialized module,
so we feel it is better off in its own repository.

The new repository URL is here:
https://github.com/zotonic/mod_geomap
doc: Add upgrade note about removed geomap module
Merge branch 'master' into mw-filestore
Merge branch 'master' into mw-filestore

Conflicts:
	doc/manuals/upgrading.rst