Add link to the docs on how to draw a bbox

[thibaultmol]

Something I realized that seems missing from the docs is that, if you're using the overpass api directly or using a client that doesn't have the ability to easily draw a bbox or use the canvas as it's bbox. It might be good to link to an external tool like: https://norbertrenner.de/osm/bbox.html

that makes this pretty easy to do

[mmd-osm]

I'm not even sure which docs you're talking about here. Can you please clarify? If it's the OSM Wiki, feel free to add it yourself.