docs(production-ready.md): Tiny typo fix

Documentation/production-ready.md

@@ -1,4 +1,4 @@
-ectd is being used successfully by many companies in production. It is,
+etcd is being used successfully by many companies in production. It is,
 however, under active development and systems like etcd are difficult to get
 correct. If you are comfortable with bleeding-edge software please use etcd and
 provide us with the feedback and testing young software needs.