updated README file for v4.0.1 release (#650)

TYPE: text only

KEYWORDS: README, release, v4.0.1

SOURCE: internal

DESCRIPTION OF CHANGES: Updated the top of the README file to indicate V4.0.1, and added a release notes section for this version, pointing to the GitHub WRF Release page.

LIST OF MODIFIED FILES:
M README

TESTS CONDUCTED: no tests conducted - text only

Author: kkeene44

README

@@ -1,5 +1,6 @@
-WRF Model Version 4.0 (June 8, 2018)
-http://wrf-model.org/users/users.php
+WRF Model Version 4.0.1 (October 2, 2018)
+
+http://www2.mmm.ucar.edu/wrf/users/
 
 ------------------------
 WRF PUBLIC DOMAIN NOTICE
@@ -40,6 +41,12 @@ doc/README.rsl_output
 doc/README.windturbine
 doc/README_test_cases
 
+V4.0.1 Release Notes (10/2/2018):
+-------------------
+
+- For more information on the WRF V4.0.1 release, visit the WRF GitHub Release Page:
+  https://github.com/wrf-model/WRF/releases
+
 V4.0 Release Notes (6/8/2018):
 -------------------