Added Spark book (#7904)

* Added Spark book

* Added authors and format

books/free-programming-books-langs.md

@@ -2325,6 +2325,7 @@ That section got so big, we decided to split it into its own file, the [BY SUBJE
 
 * [Databricks Spark Knowledge Base](https://www.gitbook.com/book/databricks/databricks-spark-knowledge-base/details)
 * [Databricks Spark Reference Applications](https://www.gitbook.com/book/databricks/databricks-spark-reference-applications/details)
+* [Learning Spark: Lightning-Fast Data Analytics](https://pages.databricks.com/rs/094-YMS-629/images/LearningSpark2.0.pdf) - Jules S. Damji, Brooke Wenig, Tathagata Das, Denny Lee (PDF)
 * [Mastering Apache Spark](https://www.gitbook.com/book/jaceklaskowski/mastering-apache-spark/details)