Fix snapshot description and change reason field

[ayushjain17]

Having both here for snapshot table seems wrong

ideally we should use the change_reason of the action which triggered this snapshot as the description for that snapshot, right ? as that change reason is what is defining that particular entry of snapshot
(snapshot table is immutable)

so having, change_reason does not make sense for snapshot table

Originally posted by @ayushjain17 in #333 (comment)