[1.8.x] Fixed #24750 -- Updated two contrib.gis comment links

Backport of 783572ab from master

django/contrib/gis/geos/__init__.py

 """
 The GeoDjango GEOS module.  Please consult the GeoDjango documentation
-for more details:
-  http://geodjango.org/docs/geos.html
+for more details: https://docs.djangoproject.com/en/dev/ref/contrib/gis/geos/
 """
 __all__ = ['HAS_GEOS']
 

django/contrib/gis/utils/layermapping.py

@@ -4,7 +4,7 @@
  vector files (e.g. SHP files) to Geographic-enabled Django models.
 
  For more information, please consult the GeoDjango documentation:
-   http://geodjango.org/docs/layermapping.html
+   https://docs.djangoproject.com/en/dev/ref/contrib/gis/layermapping/
 """
 import sys
 from decimal import Decimal, InvalidOperation as DecimalInvalidOperation