Trivial change: Update comments in activate about what running hash -r does (GH-125385)

Update comments about what running hash -r does

The old comment said "hash -r" forgets "past commands." However, the documentation for "hash" states that it forgets past locations. The old comment was, in my opinion, confusing. This is because it could be interpreted to mean it does something to the command history (HISTORY/HISTFILE etc) vs the cache of locations.