screenshot: mention 2.6 changes in docs
screenshot: mention 2.6 changes in docs

Update issue 733
Status: Review
Cc: pekka.klarck

userzimmermann/robotframework-python3,Senseg/robotframework,userzimmermann/robotframework-python3,userzimmermann/robotframework-python3,Senseg/robotframework,Senseg/robotframework,userzimmermann/robotframework-python3,Senseg/robotframework,Senseg/robotframework,userzimmermann/robotframework-python3