[SPARK-4701] Typo in sbt/sbt

Modified typo.

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

Closes #3560 from tsudukim/feature/SPARK-4701 and squashes the following commits:

ed2a3f1 [Masayoshi TSUZUKI] Another whitespace position error.
1af3a35 [Masayoshi TSUZUKI] [SPARK-4701] Typo in sbt/sbt