Update README.md

Author: LBeghini

README.md

@@ -22,10 +22,10 @@ Also, to make it easier to download the source code, [releases](https://github.c
 
 ### Creational patterns
 - [ ] Abstract factory
-- [x] [Builder](https://github.com/LBeghini/Java-Design-Patterns/releases/tag/1.builder)
+- [x] [Builder](https://github.com/LBeghini/Java-Design-Patterns/tree/1-builder)
 - [ ] Factory method
-- [ ] Prototype
-- [x] [Singleton](https://github.com/LBeghini/Java-Design-Patterns/releases/tag/1.singleton)
+- [x] [Prototype](https://github.com/LBeghini/Java-Design-Patterns/tree/2-prototype)
+- [x] [Singleton](https://github.com/LBeghini/Java-Design-Patterns/tree/1-singleton)
 
 ### Structural patterns
 - [ ] Adapter