Preset Railway=milstone uses wrong combination for distance tag

[tomasmarklund]

According to the wiki, the tag railway=milestone should be combined with railway:position=*, not distance=* as the preset in JOSM now provides.

​https://wiki.openstreetmap.org/wiki/Tag:railway%3Dmilestone

Taginfo gives a clear hint as to what is mostly common used:

73691 railway:position=*, vs 3704 distance=*

​https://taginfo.openstreetmap.org/tags/railway=milestone#combinations

Please change the preset from distance=* to railway:position=*

The label in the dialog box should also be changed to "Position (kilometers) instead of "Distance (kilometers)"