update README

Author: jedwards4b

README.md

@@ -12,3 +12,9 @@ contact cislhelp and request access if you are new to the group.
 As owner of the files in /glade/campaign/cesm/cesmdata/inputdata run script relink.py, this will remove the files from /glade/campaign/cesm/cesmdata/inputdata
 and replace them with links to the published data location.  /glade/campaign/collections/gdex/data/d651077/cesmdata/inputdata/
 
+Filenames and metadata:
+
+There is a good description of metadata that should be included in inputdata files here:  https://www.cesm.ucar.edu/models/cam/metadata
+
+Filenames should be descriptive and should contain the date the file was created. Files published in inputdata should never be overwritten.
+Replacement files should be different at least by creation date.