Add streaming example [ci skip]

Author: sferik

.yardopts

@@ -12,4 +12,5 @@ examples/AllTweets.md
 examples/Configuration.md
 examples/RateLimiting.md
 examples/Search.md
+examples/Streaming.md
 examples/Update.md

examples/Streaming.md

@@ -0,0 +1,15 @@
+# Streaming
+
+This example assumes you have a configured Twitter Streaming `client`.
+Instructions on how to configure a client can be found in
+[examples/Configuration.md][cfg].
+
+[cfg]: https://github.com/sferik/twitter/blob/master/examples/Configuration.md
+
+Here's a simple example of how to stream tweets from San Francisco:
+
+```ruby
+client.filter(:locations => "-122.75,36.8,-121.75,37.8") do |tweet|
+  puts tweet.text
+end
+```