updated disclaimer to provisional

DISCLAIMER.md

 # Disclaimer
 
-This software has been approved for release by the U.S. Geological Survey
-(USGS). Although the software has been subjected to rigorous review, the USGS
-reserves the right to update the software as needed pursuant to further analysis
-and review. No warranty, expressed or implied, is made by the USGS or the U.S.
-Government as to the functionality of the software and related material nor
-shall the fact of release constitute any such warranty. Furthermore, the
-software is released on condition that neither the USGS nor the U.S. Government
-shall be held liable for any damages resulting from its authorized or
-unauthorized use.
+This software is preliminary or provisional and is subject to revision. It is
+being provided to meet the need for timely best science. The software has not
+received final approval by the U.S. Geological Survey (USGS). No warranty,
+expressed or implied, is made by the USGS or the U.S. Government as to the
+functionality of the software and related material nor shall the fact of release
+constitute any such warranty. The software is provided on the condition that
+neither the USGS nor the U.S. Government shall be held liable for any damages
+resulting from the authorized or unauthorized use of the software.