Add best practice: Headsign and route name examples

[giocorti]

This is one of 5 PRs that incorporates a recommendation from the GTFS best practices.

This PR adds examples detailing proper headsign and route name conventions

The 4 related PRs can are:

• Specifics about stop_headsign
• Specifics about in-seat transfers
• stop_id is not rider facing
• Include arrival and departure times when possible

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[e-lo]

This should probably be moved to mobilitydata/gtfs-ba?

cc: @scmcca