[1.8.x] Fixed #24144 -- Documented that GEOSGeometry.envelope can return a point
[1.8.x] Fixed #24144 -- Documented that GEOSGeometry.envelope can return a point

Thanks Manel Clos for the report.
Backport of 1379165b35 from master.

pquentin/django,h4r5h1t/django-hauthy,h4r5h1t/django-hauthy,h4r5h1t/django-hauthy,pquentin/django,pquentin/django,h4r5h1t/django-hauthy