Add missing docstrings

src/include/pretty.sh

@@ -246,6 +246,9 @@ _pretty__get_frontend() {
 }
 
 _pretty__is_frontend() {
+    #
+    # True if $fname is one of our "frontends"
+    #
     case "$fname" in
         debug)      return 0 ;;
         debug_pipe) return 0 ;;
@@ -259,6 +262,9 @@ _pretty__is_frontend() {
 }
 
 _pretty__is_internal() {
+    #
+    # True if $fname is our internal function
+    #
     case "$fname" in
         _pretty__*) return 0 ;;
         *)          return 1 ;;