remove bad reference from _CoqProject

_CoqProject

 -Q theories reloc
-# We sometimes want to locally override notation (e.g. in proofmode/base.v, bi/embedding.v), and there
-# is no good way to do that with scopes.
+# We sometimes want to locally override notation, and there is no good way to do that with scopes.
 -arg -w -arg -notation-overridden
 # change_no_check does not exist yet in 8.9.
 -arg -w -arg -convert_concl_no_check