[SPARK-13874][DOC] Remove docs of streaming-akka, streaming-zeromq, streaming-mqtt and streaming-twitter

## What changes were proposed in this pull request?

This PR removes all docs about the old streaming-akka, streaming-zeromq, streaming-mqtt and streaming-twitter projects since I have already copied them to https://github.com/spark-packages

Also remove mqtt_wordcount.py that I forgot to remove previously.

## How was this patch tested?

Jenkins PR Build.

Author: Shixiong Zhu <shixiong@databricks.com>

Closes #11824 from zsxwing/remove-doc.

1 files changed, 0 insertions, 59 deletions

diff --git a/examples/src/main/python/streaming/mqtt_wordcount.py b/examples/src/main/python/streaming/mqtt_wordcount.py
deleted file mode 100644
index abf9c0e21d..0000000000
--- a/examples/src/main/python/streaming/mqtt_wordcount.py
+++ /dev/null
@@ -1,59 +0,0 @@
-#
-# Licensed to the Apache Software Foundation (ASF) under one or more
-# contributor license agreements.  See the NOTICE file distributed with
-# this work for additional information regarding copyright ownership.
-# The ASF licenses this file to You under the Apache License, Version 2.0
-# (the "License"); you may not use this file except in compliance with
-# the License.  You may obtain a copy of the License at
-#
-#    http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-#
-
-"""
- A sample wordcount with MqttStream stream
- Usage: mqtt_wordcount.py <broker url> <topic>
-
- To run this in your local machine, you need to setup a MQTT broker and publisher first,
- Mosquitto is one of the open source MQTT Brokers, see
- http://mosquitto.org/
- Eclipse paho project provides number of clients and utilities for working with MQTT, see
- http://www.eclipse.org/paho/#getting-started
-
- and then run the example
-    `$ bin/spark-submit --jars \
-      external/mqtt-assembly/target/scala-*/spark-streaming-mqtt-assembly-*.jar \
-      examples/src/main/python/streaming/mqtt_wordcount.py \
-      tcp://localhost:1883 foo`
-"""
-
-import sys
-
-from pyspark import SparkContext
-from pyspark.streaming import StreamingContext
-from pyspark.streaming.mqtt import MQTTUtils
-
-if __name__ == "__main__":
-    if len(sys.argv) != 3:
-        print >> sys.stderr, "Usage: mqtt_wordcount.py <broker url> <topic>"
-        exit(-1)
-
-    sc = SparkContext(appName="PythonStreamingMQTTWordCount")
-    ssc = StreamingContext(sc, 1)
-
-    brokerUrl = sys.argv[1]
-    topic = sys.argv[2]
-
-    lines = MQTTUtils.createStream(ssc, brokerUrl, topic)
-    counts = lines.flatMap(lambda line: line.split(" ")) \
-        .map(lambda word: (word, 1)) \
-        .reduceByKey(lambda a, b: a+b)
-    counts.pprint()
-
-    ssc.start()
-    ssc.awaitTermination()