add comment about autogeneration

Author: wyattscarpenter

docs/source/command_line.rst

@@ -767,6 +767,11 @@ of the above sections.
     over time.
 
     .. include:: strict_list.rst
+    ..
+        The above file is autogenerated and included during html generation.
+        (That's an include directive, and this is a comment.)
+        It would be fine to generate it at some other time instead,
+        theoreticaly, but we already had a convenient hook during html gen.
 
 
 .. option:: --disable-error-code