Add OSX development tip to README

README.md

@@ -123,6 +123,21 @@ If you want your user to have super privileges:

    ALTER USER cosmopolitan WITH SUPERUSER;

Tip for local development using (OS X)

Install [GDAL binaries]() for OSX, and add the following to .bash_profile:

    GDAL_LIBRARY_PATH="/Library/Frameworks/GDAL.framework/Versions/1.11/GDAL"
    GEOS_LIBRARY_PATH="/Library/Frameworks/GEOS.framework/Versions/3/GEOS"

Then add the following to your local Django settings:

    # GeoDjango fixes
    GDAL_LIBRARY_PATH = os.environ.get('GDAL_LIBRARY_PATH')
    GEOS_LIBRARY_PATH = os.environ.get('GEOS_LIBRARY_PATH')

(see https://www.alextomkins.com/2017/08/fixing-gdal-geos-django-macos/ for details)

## Starting from scratch

### Requirements