## 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.
In the course of https://issues.apache.org/jira/browse/LEGAL-226 it came to light that the guidance at http://www.apache.org/dev/licensing-howto.html#permissive-deps means that permissively-licensed dependencies has a different interpretation than we (er, I) had been operating under. "pointer ... to the license within the source tree" specifically means a copy of the license within Spark's distribution, whereas at the moment, Spark's LICENSE has a pointer to the project's license in the other project's source tree.
The remedy is simply to inline all such license references (i.e. BSD/MIT licenses) or include their text in "licenses" subdirectory and point to that.
Along the way, we can also treat other BSD/MIT licenses, whose text has been inlined into LICENSE, in the same way.
The LICENSE file can continue to provide a helpful list of BSD/MIT licensed projects and a pointer to their sites. This would be over and above including license text in the distro, which is the essential thing.
Author: Sean Owen <sowen@cloudera.com>
Closes#8919 from srowen/SPARK-10833.