Update section 'When do i need a new Microversion?'
Update section 'When do i need a new Microversion?'

It is been agreed upon that if a new feature is proposed
sharing similarities (in terms of intention and code)
with a previously merged feature then both the features
can be clubbed together within the same (previous feature)
microversion given that the previously merged feature isn't
released.

Change-Id: I80216f9c2645ece1ea4c57550936a247440a5a82

mahak/cinder,openstack/cinder,openstack/cinder,mahak/cinder