Apply suggestions from code review

Co-authored-by: bjorn3 <bjorn3@users.noreply.github.com>

Author: Diggsey

src/design_notes/fn_type_trait_impls.md

@@ -22,6 +22,7 @@ exposed via trait implementations and implicit conversions.
   corresponding _function pointer_ type.
 
 This design note attempts to capture a range of proposed solutions, and some of the feedback regarding those solutions. This design note does not intend to favor any specific solutions, just reflect past discussions. The presence or absence of any particular feedback in this document does not necessarily serve to favor or disfavor any particular solution.
+
 ## Motivation
 
 There are several cases where it is necessary to write a [thunk]. A thunk