Clarify benefits section

[yndajas]

Some benefits are available to staff from their first day, e.g. eyecare, while others are available after passing probation

The benefits page starts by saying "All benefits are available to the dxw team members after they’ve successfully passed their probationary period.", which is a little misleading

Action: break down/clarify which benefits are available when

Note: the people team may already have this on their radar to update, but I'm opening an issue to keep a record that it needs addressing