Update CHANGES in preparation for 0.4.1
Update CHANGES in preparation for 0.4.1

Signed-off-by: Mark Somerville <f1b5a91d4d6ad523f2610114591c007e75d15084@scottishclimbs.com>

rapid7/rb-readline,abinoam/rb-readline,ConnorAtherton/rb-readline,mattn/rb-readline