Clarify Start and End point documentation

[e-lo]

From a tester:

Start and End points through the example looks like it is defined using the cross-roads name. I think it is more valuable to have Milepost rather than a cross-roadname. This will also help to calculate length in miles of the facility. Thus, can be used while analyzing big projects and small projects separately. Also, I doubt that a segment is always constructed/altered between two crossroads. In case of Wisconsin, we did not even have information of the road the project was built on other than functional class.

[e-lo]

Mileposts are only valid for freeways/longer distance facilities.
Start and End are flexible and could be mileposts, lat/long, or cross roads.

Suggest that we just clarify that it could be any of these things.