update install instructions to use GitHub

Author: timgraham

README.md

@@ -6,30 +6,9 @@ explore and build.
 
 ## Install and usage
 
-Use the version of `django-mongodb` that corresponds to your version of
-Django. For example, to get the latest compatible release for Django 5.0.x:
+The development version of this package supports Django 5.0.x. To install it:
 
-`pip install django-mongodb==5.0.*`
-
-The minor release number of Django doesn't correspond to the minor release
-number of django-mongodb. Use the latest minor release of each.
-
-While django-mongodb only has pre-releases (alphas or betas), you'll see an
-error with a list of the available versions. In that case, include `--pre` to
-allow `pip` to install the latest pre-release.
-
-For example, if django-mongodb 5.0 alpha 1 is the latest available version
-of the 5.0 release series:
-
-```
-$ pip install django-mongodb==5.0.*
-ERROR: Could not find a version that satisfies the requirement
-django-mongodb==5.0.* (from versions: ..., 5.0a1)
-
-$ pip install --pre django-mongodb==5.0.*
-...
-Successfully installed ... django-mongodb-5.0a1 ...
-```
+`pip install git+https://github.com/mongodb-labs/django-mongodb`
 
 Configure the Django `DATABASES` setting similar to this: