Updating docs.

doc/hfsm_design.md

@@ -4,6 +4,4 @@ This implementation requires n + 2 stack frames, where n is the depth of the hie
 
 ## 2. hfsm_hardcoded: Hardcoded hierarchy definition
 
-Stack usage improvements:
-
-1. Superstate event handling (`default:` switch case) can be postponed after the stack-frame exits, within the `hfsm_post_event()` function by using return codes. The deep CPU stack can be converted into a `for` loop.
+1. Constant stack usage: superstate event handling (`default:` switch case) can be postponed after the stack-frame exits, within the `hfsm_post_event()` function by using return codes. The deep CPU stack can be converted into a `for` loop.