[SPARK-4421] Wrong link in spark-standalone.html

Modified the link of building Spark.

Author: Masayoshi TSUZUKI <tsudukim@oss.nttdata.co.jp>

Closes #3279 from tsudukim/feature/SPARK-4421 and squashes the following commits:

56e31c1 [Masayoshi TSUZUKI] Modified the link of building Spark.
Fix typo in Spark SQL docs.

Author: Andy Konwinski <andykonwinski@gmail.com>

Closes #3611 from andyk/patch-3 and squashes the following commits:

7bab333 [Andy Konwinski] Fix typo in Spark SQL docs.