Work towards #56: Add permalink to every pattern

This makes cleaner URLs thanks to jekyll

object-pool/index.md

@@ -2,6 +2,7 @@
 layout: pattern
 title: Object Pool
 folder: object-pool
+permalink: /patterns/object-pool/
 categories: pattern_cat
 tags: pattern_tag
 ---
@@ -16,4 +17,4 @@ are in use and which are available.
 **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)
+* you need a large number of short-lived objects (memory fragmentation)