Add note about SymbolScale to Label Size Documentation

[ben]

In order to get label scaling to work a SYMBOLSCALE (Denominator at which the size setting is used) needs to be set.

This is documented in the Layer description, but there is no reference to this requirement in the label documentation.

I would suggest adding the following note (basically written by Steve Lime) to the Label page either at the top, or under the SIZE entry:

To use scaling of label sizes, you need to set a SYMBOLSCALE at the layer level. That's the scale denominator (e.g. 100000) at which a label SIZE will be equal to what you set in the mapfile. As you move away from that value the labels will get larger or smaller.

cheers

Ben

[havatv]

Fixed for 6.0 and trunk documentation in r12047.