Point to a rewritten version of the images repo

This contains a svg image in place of the original flow.png for PHS

Author: billsacks

Externals_CLM.cfg

@@ -16,7 +16,7 @@ required = True
 local_path = doc/images
 protocol = git
 repo_url = https://github.com/ESCOMP/CTSM-doc-images.git
-hash = 9e12e5531d8cd3f2e9c6a0154dba8289ffd32c7f
+hash = 476c694359e76c5054958e1397b8fa18aa0ff3e0
 required = False
 
 [externals_description]