DOC: Clarify installing released version vs. dev versions
DOC: Clarify installing released version vs. dev versions

snario/geopandas,jorisvandenbossche/geopandas,fonnesbeck/geopandas,IamJeffG/geopandas,micahcochran/geopandas,jorisvandenbossche/geopandas,koldunovn/geopandas,ozak/geopandas,geopandas/geopandas,urschrei/geopandas,jdmcbr/geopandas,perrygeo/geopandas,jorisvandenbossche/geopandas,geopandas/geopandas,ozak/geopandas,jdmcbr/geopandas,kwinkunks/geopandas,micahcochran/geopandas,geopandas/geopandas,maxalbert/geopandas,scw/geopandas