fix doc issue

Author: urbytes21

src/patterns/creational/FactoryMethod.cpp

@@ -6,6 +6,7 @@
 // (*)  when you don’t know beforehand the exact types and dependencies of the objects your code should work with.
 // (**) when you want to provide users of your library or framework with a way to extend its internal components.
 // (***)when you want to save system resources by reusing existing objects instead of rebuilding them each time.
+
 // UML: docs/uml/patterns_creational_factorymethod.drawio.svg
 
 #include <iostream>

src/patterns/creational/Singleton.cpp

@@ -6,6 +6,8 @@
 // (*)  when a class in your program should have just a single instance available to all clients; for example, a single database object shared by different parts of the program.
 // (**) when you need stricter control over global variables.
 
+// UML: docs/uml/patterns_creational_singleton.drawio.svg
+
 #include <iostream>
 
 namespace