some typo and grammar fixes to osm.rst
some typo and grammar fixes to osm.rst

markles/GeoGit,markles/GeoGit,boundlessgeo/GeoGig,markles/GeoGit,markles/GeoGit,boundlessgeo/GeoGig,markles/GeoGit,boundlessgeo/GeoGig,annacarol/GeoGig,annacarol/GeoGig,annacarol/GeoGig