Work towards #56: Splitting up the README

I did the job and splitted up the readme, hopefully everything was
splitted correctly...

multiton/index.md

@@ -0,0 +1,16 @@
+---
+layout: pattern
+title: Multiton
+folder: multiton
+categories: pattern_cat
+tags: pattern_tag
+---
+
+**Intent:** Ensure a class only has limited number of instances, and provide a
+global point of access to them.
+
+![alt text](./etc/multiton.png "Multiton")
+
+**Applicability:** Use the Multiton pattern when
+
+* there must be specific number of instances of a class, and they must be accessible to clients from a well-known access point