DOC: Add example docs for plotting transparent polygons (#1170)
DOC: Add example docs for plotting transparent polygons (#1170)

* Add example docs for plotting transparent polygons

* Add explanation for plotting transparent polygons

* Update doc/source/mapping.rst

Co-Authored-By: Martin Fleischmann <a8c4b4d5dc6da0388bc7b381336ae1b751c37807@users.noreply.github.com>

jorisvandenbossche/geopandas,jorisvandenbossche/geopandas,jorisvandenbossche/geopandas,geopandas/geopandas,jdmcbr/geopandas,jdmcbr/geopandas,geopandas/geopandas,geopandas/geopandas