translator: print additional unknown-node feedback

When an unknown node is detected by this extension, attempt to print
the document as well as the line number where the issue has occurred.
This should provide users a better understanding where the origin of an
unknown node occurs.

Signed-off-by: James Knight <james.d.knight@live.com>

sphinxcontrib/confluencebuilder/translator.py

@@ -165,7 +165,12 @@ def unknown_visit(self, node):
             handler[node_name](self, node)
             raise nodes.SkipNode
 
-        self.warn('unknown node: ' + node_name)
+        if node.source:
+            lpf = f'#{node.line}' if node.line else ''
+            self.warn(f'unknown node {node_name}: {node.source}{lpf}')
+        else:
+            self.warn(f'unknown node {node_name}: {self.docname}')
+
         raise nodes.SkipNode
 
     # ---------