Add trailheads data

[stdavis]

https://mail.google.com/mail/u/1/#inbox/FMfcgxwBWTFVpQGPXmDskKbRvMCDNrhR

[steveoh]

What sort of link is this?

[stdavis]

In early 2019, Seth Ackroyd told me that @nathankota wanted trailheads added to locate. He gave me some queries to run on the trailheads to get ones that were within 1/2 mile of major roads and an SVG from Aaron M. I put it on my TODO list and it got buried and I never got to it. 😬

@nathankota Is this still something that you want to happen? I'll attach the mxd and svg so that we have them for future reference.
Archive.zip

[nathankota]

This is going too far back for me to remember! Sounds like busy work. Let's keep it open for a while longer as a reminder and see what happens in the future.