add comments to ch15

Author: Xronophobe

chapter_15_advanced_forms.asciidoc

@@ -363,6 +363,8 @@ and discuss what to do if we run into migrations and data integrity issues at th
 
 Now if we change our duplicates test to do a `.save` instead of a
 `.full_clean`...
+// CSANAD: maybe the migrations are a little too long of an insertion between
+// the premise (some errors show up upon save() and actually trying it out.
 
 [role="sourcecode"]
 .src/lists/tests/test_models.py