Update no-orphaned-subclasses.sparql

Based on the updates provided by @swartik, thank you. Tell me if there are any remaining edits that need to be made.

.github/deployment/sparql/no-orphaned-subclasses.sparql

@@ -1,15 +1,12 @@
 # Title: 
 #     No Orphaned Subclasses
 # Constraint Description: 
-#     All classes must have some parent class. The only result otherwise should be “entity”.
+#     All CCO classes must have a superclass.
 # Severity:
-#     Warning
+#     Error
 # Author:
 #	 github.com/swartik
 
-Severity:
-    (select "Warning" or "Error")
-
 PREFIX owl: <http://www.w3.org/2002/07/owl#>
 PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
 
@@ -18,4 +15,5 @@ WHERE {
   ?cls a owl:Class
   FILTER isIRI(?cls)
   FILTER NOT EXISTS { ?cls rdfs:subClassOf ?supercls }
+  FILTER (?cls != <http://purl.obolibrary.org/obo/BFO_0000001>)
 }