KAFKA-3461: Fix typos in Kafka web documentations.

This PR fixes 8 typos in HTML files of `docs` module. I wrote explicitly here since Github sometimes does not highlight the corrections on long lines correctly.
- docs/api.html: compatability => compatibility
- docs/connect.html: simultaneoulsy => simultaneously
- docs/implementation.html: LATIEST_TIME => LATEST_TIME, nPartions => nPartitions
- docs/migration.html: Decomission => Decommission
- docs/ops.html: stoping => stopping, ConumserGroupCommand => ConsumerGroupCommand, youre => you're

Author: Dongjoon Hyun <dongjoon@apache.org>

Reviewers: Ismael Juma

Closes #1138 from dongjoon-hyun/KAFKA-3461