--- a/mercurial/help.py	Tue Apr 18 14:51:32 2017 -0700
+++ b/mercurial/help.py	Wed Apr 19 17:04:22 2017 -0700
@@ -203,7 +203,8 @@
 
 def internalshelp(ui):
     """Generate the index for the "internals" topic."""
-    lines = []
+    lines = ['To access a subtopic, use "hg help internals.{subtopic-name}"\n',
+             '\n']
     for names, header, doc in internalstable:
         lines.append(' :%s: %s\n' % (names[0], header))