[FEATURE] Clarify documentation on CLI function arguments

[hrecht]

Is your feature request related to a problem? Please describe.
Thanks for the incredibly useful tool!

I recently had a tough time troubleshooting why my tiles only went up to zoom level 14, and had to spend a long time reading through old Github issues (#128) to find that higher zooms weren't supported. Though it seems that zoom 15 now is, per #303? It is currently unclear from the documentation what the maximum supported zoom level is, and if zoom 15 is supported, how to use it.

Describe the solution you'd like
It would be very helpful to have all of the function arguments with default settings and options documented clearly in the README or elsewhere. Right now the README says "Some common arguments:" at

planetiler/README.md

Line 102 in 4920b34

Some common arguments:

without listing all of the arguments and what their options are. I see some more documentation for fully custom files at https://github.com/onthegomap/planetiler/tree/main/planetiler-custommap but not for simple use of the CLI with the default profile.

The documentation could read something like:
--maxzoom: Set the maximum tile zoom of the output file, an integer.
default value: 14
options: 1 - 15

I'd be up to help contribute to the README if it's helpful, but would need some guidance on what those arguments and options are.

[msbarry]

Thanks for opening the issue, this is definitely a gap today. Ideally I'd like the code that defines the cli args, descriptions, and default values be the source of truth and we could generate a snapshot for the docs from that. There's a --help option today that prints the args and exits. Maybe we could have a variation that dumps in markdown format for the docs?

[hrecht]

That would be great! Somehow I missed the --help option, my bad.

Also (this probably exists somewhere already) - but it would also be great to link to a list of the predefined geographic region names available for the --area argument, such as monaco. I haven't found that on https://download.geofabrik.de/ and had to do some experimenting for a few regions to get the names to work.