Fixes KStreams testing docs use non-existent method pipe
Minor fix of apache/kafka-site#210
Reviewers: John Roesler Bill Bejeck
@@ -99,7 +99,7 @@ TopologyTestDriver testDriver = new TopologyTestDriver(topology, props);
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<pre>
ConsumerRecordFactory&lt;String, Integer&gt; factory = new ConsumerRecordFactory&lt;&gt;("input-topic", new StringSerializer(), new IntegerSerializer());
-testDriver.pipe(factory.create("key", 42L));
+testDriver.pipeInput(factory.create("key", 42L));
</pre>
<p>
To verify the output, the test driver produces <code>ProducerRecord</code>s with key and value type
