Add ISIS ROR pending status

ISIS currently has no ROR ID.  The facilities entry is updated to record
the corresponding issue, requesting a new ROR ID.

_data/facilities.yml

@@ -250,6 +250,8 @@
 
 ## ISIS Neutron and Muon Source ##
 - short-name: ISIS
+  # ROR ID is pending; see
+  # https://github.com/ror-community/ror-updates/issues/5124
   adoption:
     adopted:
       - OAI-PMH