Add a warning to schedule docs

[spacey-sooty]

See wpilibsuite/allwpilib#7073

[sciencewhiz]

This one was merged on the WPILib side, but the message was changed, so this PR should be updated.

[TheTripleV]

Though, note that pathplanner docs use .schedule https://github.com/mjansen4857/pathplanner/blob/main/examples/java/src/main/java/frc/robot/RobotContainer.java#L113
on a network button and for scheduling the autonomous command

[spacey-sooty]

Though, note that pathplanner docs use .schedule https://github.com/mjansen4857/pathplanner/blob/main/examples/java/src/main/java/frc/robot/RobotContainer.java#L113

on a network button and for scheduling the autonomous command

They are using Command.schedule which iirc is getting deprecated :/