fixed spelling errors in documentation

changed "form" to "from" in 3 documentation entries for Kafka integration

Author: Peter Klipfel <peter@klipfel.me>

Closes #3691 from peterklipfel/master and squashes the following commits:

0fe7fc5 [Peter Klipfel] fixed spelling errors in documentation

(cherry picked from commit 2a2983f7c5edce8e4d1d7592adcf227cbd462ae9)
Signed-off-by: Josh Rosen <joshrosen@databricks.com>