use Genny to generate typed lists, based on Go standard library code

internal/utils/linkedlist/README.md

@@ -0,0 +1,11 @@
+# Usage
+
+This is the Go standard library implementation of a linked list 
+(https://golang.org/src/container/list/list.go), modified such that genny
+(https://github.com/cheekybits/genny) can be used to generate a typed linked
+list.
+
+To generate, run
+```
+genny -pkg $PACKAGE -in linkedlist.go -out $OUTFILE gen Item=$TYPE
+```