add lisp packages

lisp/yasnippet-snippets/snippets/c++-mode/operator[]

@@ -0,0 +1,9 @@
+# -*- mode: snippet -*-
+# name: operator[]
+# key: []
+# group: operator overloading
+# --
+${1:Name}& operator[](${2:int index})
+{
+        $0
+}