Don't require numfig to use :numref: on sections

Tweak logic that rejects a :numref: if numfig is not on to bypass this
check if the reference is a section. Section numbers are applied
independent of numfig, so the check is not needed, and makes it
needlessly difficult to use :numref: if the user only cares about using
it on sections.

sphinx/domains/std.py

@@ -715,15 +715,15 @@ class StandardDomain(Domain):
         if not docname:
             return None
 
-        if env.config.numfig is False:
-            logger.warning('numfig is disabled. :numref: is ignored.', location=node)
-            return contnode
-
         target_node = env.get_doctree(docname).ids.get(labelid)
         figtype = self.get_figtype(target_node)
         if figtype is None:
             return None
 
+        if figtype != 'section' and env.config.numfig is False:
+            logger.warning('numfig is disabled. :numref: is ignored.', location=node)
+            return contnode
+
         try:
             fignumber = self.get_fignumber(env, builder, figtype, docname, target_node)
             if fignumber is None: