Add reference to commercial/open source Stream Analytics Query Languages

[emanueledellavalle]

• https://learn.microsoft.com/en-us/stream-analytics-query/stream-analytics-query-language-reference
• https://beam.apache.org/
  • https://colab.research.google.com/github/apache/beam/blob/master/examples/notebooks/interactive-overview/windowing.ipynb
• https://aws.amazon.com/pm/kinesis/
• https://www.ibm.com/products/streaming-analytics
• https://docs.oracle.com/en/middleware/fusion-middleware/osa/18.1/understanding-stream-analytics/overview-oracle-streaming-analytics.html
• https://www.confluent.io/blog/getting-started-with-apache-flink-sql/