[SPARK-3765][Doc] Add test information to sbt build docs

Add testing with sbt to doc ```building-spark.md```

Author: scwf <[email protected]>

Closes apache#2629 from scwf/sbt-doc and squashes the following commits:

fd9cf29 [scwf] add testing with sbt to docs

Author: scwf

docs/building-spark.md

@@ -171,6 +171,21 @@ can be set to control the SBT build. For example:
 
     sbt/sbt -Pyarn -Phadoop-2.3 assembly
 
+# Testing with SBT
+
+Some of the tests require Spark to be packaged first, so always run `sbt/sbt assembly` the first time.  The following is an example of a correct (build, test) sequence:
+
+    sbt/sbt -Pyarn -Phadoop-2.3 -Phive assembly
+    sbt/sbt -Pyarn -Phadoop-2.3 -Phive test
+
+To run only a specific test suite as follows:
+
+    sbt/sbt -Pyarn -Phadoop-2.3 -Phive "test-only org.apache.spark.repl.ReplSuite"
+
+To run test suites of a specific sub project as follows:
+
+    sbt/sbt -Pyarn -Phadoop-2.3 -Phive core/test
+
 # Speeding up Compilation with Zinc
 
 [Zinc](https://github.com/typesafehub/zinc) is a long-running server version of SBT's incremental