PHOENIX-5892 Add code coverage steps in build documentation
PHOENIX-5892 Add code coverage steps in build documentation

Signed-off-by: Chinmay Kulkarni <23bf4e8569cab722a6eded6d385f17cd8ad6a222@apache.org>

apache/phoenix,apurtell/phoenix,apurtell/phoenix,ankitsinghal/phoenix,ankitsinghal/phoenix,ankitsinghal/phoenix,ankitsinghal/phoenix,apache/phoenix,apurtell/phoenix,apurtell/phoenix,apache/phoenix,apache/phoenix,apache/phoenix,apurtell/phoenix,ankitsinghal/phoenix