Update README.md

Fix incorrect  pod spec
Adjust the regexp so that we can handle extra sub versions.
Rename util.config.Watcher -> util.config.Broadcaster.

Watch is a widely used term in the codebase, which doesn't capture
the key feature of this type: broadcasting a change to several
listeners.
Rename watch.Mux -> watch.Broadcaster

A few reasons:
- Mux is already widely used in the codebase to refer to a http handler mux.
- Original meaning of Mux was something which sent a chose one of several inputs to
  and output.  This sends one output to all outputs.  Broadcast captures that idea
  better.
- Aligns with similar class config.Broadcaster (see #2747)
Merge pull request #2748 from erictune/clean7

Rename watch.Mux -> watch.Broadcaster
Merge pull request #2747 from erictune/cleanup6

Rename util.config.Watcher -> util.config.Broadcaster.
Merge pull request #2731 from brendandburns/bash

Adjust the regexp so that we can handle extra sub versions.
Merge pull request #2626 from jasonkuhrt/patch-1

Fix incorrect pod spec in tutorial
bump(gopkg.in/v2/yaml): d466437aa4adc35830964cffc5b5f262c63ddcb4
Remove uint64 bitshift workaround