Remove or fix floating point example in SpinBox

The floating point example is a dud. It can visualize a floating point value but the example only increments the major part of the floating point. Not the, as one would expect, the fractional part.

Therefore either remove it or fix the example as the current example is useless and gives the wrong impression.

Note: incrementing a visual value from "1.10" should go to "1.11" to make sense. Instead the example on increment goes to "2.10" making the floating part really just a static suffix of sorts.

https://doc.qt.io/qt-6/qml-qtquick-controls2-spinbox.html#details