polymorphism: reorder intro

Author: leogermond

courses/fundamentals_of_ada/180_polymorphism/01-introduction.rst

@@ -8,9 +8,6 @@ Introduction
 
 * :ada:`'Class` operator to categorize :dfn:`classes of types`
 * Type classes allow dispatching calls
-
-   - Abstract types
-   - Abstract subprograms
-
-* Runtime call dispatch vs compile-time call dispatching
+* :dfn:`Static dispatch` at compile-time (overloading)
+* :dfn:`Dynamic dispatch` at run-time