feat: add PlantUML diagram for classes in Assert

Author: Damian Rouson

doc/assert_class_diagram.puml

@@ -0,0 +1,21 @@
+@startuml
+Title Classes in the Assert Library
+
+hide empty members
+
+abstract class characterizable_t{
+  {abstract} as_character() : character(len=:), allocatable
+}
+
+class intrinsic_array_t{
+  c[] : complex
+  i[] : integer 
+  l[] : logical 
+  r[]: real
+  intrinsic_arry_t(array[..] : class(*)) : intrinsic_array_t
+  as_character() : character(len=:), allocatable
+}
+
+intrinsic_array_t .up.|> characterizable_t : implements
+
+@enduml

doc/class_diagram.puml renamed to doc/example_class_diagram.puml

@@ -24,6 +24,6 @@ class characterizable_stuff_t{
 }
 
 characterizable_stuff_t *-down- stuff_t : aggregates
-characterizable_stuff_t -up-|> characterizable_t : implements
+characterizable_stuff_t .up.|> characterizable_t : implements
 
 @enduml