They mean that the limit switch cuts the power to the motor. I have not done teardown of these, but I could imagine they have some capacitor powered circuit combined with spring to do the auto-return in case of supply power-off.
I can't speak for this particular one, but all the ones I've seen work like the Honeywell 2 port or 3 port valves.
There are no capacitors.
There's an unpowered position where the spring pulls the valve back to the default position.
The motor, a geared synchronised type, is unidirectional.
When called, it motors across to the stop microswitch. That's the 6 to 8 seconds. The switch takes the 240 volts AC off the motor and brings the diode/resistor circuit (270k from memory) into play. This stalls the motor enough to hold it in place, coupled with the gearing, to resist the spring pulls back.
If you remove power completely, the spring pulls the ball back to the default position.
Using almost no power, in the Honeywell design, is the current flowing through the diode and resistor.
In my experience, valves left in this stalled position overheat and eventually fail.
In my own heating system, Honeywell Y-Plan, I fitted a timer that cuts the power to the valve twice a day and reduces the failure likelihood.
The 3 port valve is stalled in the mid position as well as the powered position.
Internally, it's a complicated mix up of two changeover microswitches.
It's clever, but flawed.
A brand new Honeywell 4043A 22-mm valve is close to £100, so that Solid valve is a bargain.
All the answers and discussions above should help point you in the right direction.
Have you worked on your requirements and design? We aren't going to design it for you. But if you bring some work to the table we will be more than happy to offer advice and/or constructive criticism.
My special thanks to @scottcalv for all the valuable inputs.
Also I am grateful for the inputs given by @jim-p , @TomGeorge , @tigger, @Paul_KD7HB, @kmin , @hammy , and @Etienne_74
Your welcome.