Add links howto to setup IDEs for developing spark

These links make it easier for new developers to work with Spark in their IDE.

Author: kaklakariada <[email protected]>

Closes #10104 from kaklakariada/readme-developing-ide-gettting-started.

Author: kaklakariada

README.md

@@ -27,6 +27,8 @@ To build Spark and its example programs, run:
 (You do not need to do this if you downloaded a pre-built package.)
 More detailed documentation is available from the project site, at
 ["Building Spark"](http://spark.apache.org/docs/latest/building-spark.html).
+For developing Spark using an IDE, see [Eclipse](https://cwiki.apache.org/confluence/display/SPARK/Useful+Developer+Tools#UsefulDeveloperTools-Eclipse)
+and [IntelliJ](https://cwiki.apache.org/confluence/display/SPARK/Useful+Developer+Tools#UsefulDeveloperTools-IntelliJ).
 
 ## Interactive Scala Shell