improving the documentation to explain how updating values works on tabbed website

[StefanL38]

The documentation is yet pretty good.

Though there is (always) room to improve it.

If a website uses tabs updating a value of a number-element does not work with this description Number inputs can be updated from code using ESP.updateNumber().

Additionally this text does not show the parameters of the function.

What I found that works on tabbed websites is using the

ESPUI.updateControlValue(UI_ID_Number,String(myInteger));