[SPARK-7302] [DOCS] SPARK building documentation still mentions building for yarn 0.23

[srowen]

Remove references to Hadoop 0.23

CC @tgravescs Is this what you had in mind? basically all refs to 0.23?
We don't support YARN 0.23, but also don't support Hadoop 0.23 anymore AFAICT. There are no builds or releases for it.

In fact, on a related note, refs to CDH3 (Hadoop 0.20.2) should be removed as this certainly isn't supported either.

[SparkQA]

Test build #31664 has finished for PR 5863 at commit 42f5d1e.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds the following public classes (experimental):
  • abstract class ShuffleHandle(val shuffleId: Int) extends Serializable
  • * class SomethingNotSerializable
  • logDebug(s" + cloning the object $obj of class $
  • class SaslEncryption
  • static class EncryptedMessage extends AbstractReferenceCounted implements FileRegion
  • class SaslRpcHandler extends RpcHandler
  • public class SaslServerBootstrap implements TransportServerBootstrap
  • public class SparkSaslClient implements SaslEncryptionBackend
  • public class SparkSaslServer implements SaslEncryptionBackend
  • public class ByteArrayWritableChannel implements WritableByteChannel

[pwendell]

LGTM