Work towards #56: Splitting up the README

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

object-pool/index.md

@@ -0,0 +1,19 @@
+---
+layout: pattern
+title: Object Pool
+folder: object-pool
+categories: pattern_cat
+tags: pattern_tag
+---
+
+**Intent:** When objects are expensive to create and they are needed only for
+short periods of time it is advantageous to utilize the Object Pool pattern.
+The Object Pool provides a cache for instantiated objects tracking which ones
+are in use and which are available.
+
+![alt text](./etc/object-pool.png "Object Pool")
+
+**Applicability:** Use the Object Pool pattern when
+
+* the objects are expensive to create (allocation cost)
+* you need a large number of short-lived objects (memory fragmentation)