Remove old, outdated DESCRIPTION

With this gone, PyPI will now use README for its documentation,
which is a lot more relevant.

MANIFEST.in

@@ -1,4 +1,3 @@
-include DESCRIPTION.rst
 include *.md
 include *.py
 include LICENSE

setup.py

@@ -21,9 +21,9 @@
 from gwlfe.MultiUse_Fxns.Runoff.WashImperv_inner import cc as wipcc
 from gwlfe.MultiUse_Fxns.Runoff.WashPerv_inner import cc as wpcc
 
-# Get the long description from DESCRIPTION.rst
+# Get the long description from README.md
 with open(path.join(path.abspath(path.dirname(__file__)),
-                    'DESCRIPTION.rst'), encoding='utf-8') as f:
+                    'README.md'), encoding='utf-8') as f:
     long_description = f.read()
 
 tests_require = [
@@ -36,7 +36,7 @@
     version='3.1.0',
     description='A Python port of Generalized Watersheds Loading Functions - Enhanced (MapShed)',
     long_description=long_description,
-    long_description_content_type='text/x-rst',
+    long_description_content_type='text/markdown',
     url='https://github.com/WikiWatershed/gwlf-e',
     author='Azavea Inc.',
     author_email='[email protected]',