Update README.md to clarify individual configuration options.

[SirYodaJedi]

I'm still not sure quite how the internal-resolution option works (What is the syntax? Can it be used for supersampling?)
I also am not sure if I understand the values for max_anisotropy.

My confusions, however, are why I felt it necessary to clarify individual options. Obviously, some stuff needs to be cleaned up.

[SirYodaJedi]

I'll leave this here as an example (text-only) documentation for the config file. Closing because of changes in file structure.

[jdmclark]

Hi @SirYodaJedi

Thanks for submitting this. I was just creating an issue to track documenting the configuration options when I saw this pull request (#14).

Main comments:

• The list of options is getting quite long, so I think it would be better if the detailed listing was in a separate page under docs and then linked from the main readme.
• This PR doesn't document all of the options. The doc should definitely be current and complete before adding to the repository. The config parsing code is in common/config.cpp (if you can't read it, I can make a list of the ones you're missing).
• If you have time to do this, I think it would also be helpful if the guide includes pictures showing what the graphics options do. If you don't have time, that's okay too. The text doc would be good enough for a first pass.

I'm also happy to help answer any questions you have about the other options:

• max_anisotropy is a GPU vendor-defined value, and has no meaningful definition as far as I'm aware.
• internal_resolution takes either null or an ordered pair [w, h] (same as the resolution field). This lets JK render to a different resolution than the screen resolution. It's mostly useful for running the game at 2880x2160, which 4k at a 4:3 aspect ratio, but not a real resolution (at least according to my monitor).

[SirYodaJedi]

Okay. I wasn't planning on it being a full master commit anyway, just showing proof of concept.
Questions before I modify it:

• Would it go in ./doc/config.md?
• I see there are options for data_path and log_path. These don't have defaults in jkgm.json, so I'm not sure what the syntax is.
• So max_anisotropy doesn't actually set the level of anisotropic filtering, but just that it is enabled? So changing it to 16.0 (As I am accustomed to always setting 16x AF) is pointless? And do any values disable anisotropic filtering (if someone really needed to do that for some reason)?
• I'm not quite sure what you mean by "not a real resolution". Are you just referring to the fact that your monitor accepts 3840x2160, but not 2880x2160? I'll do some more testing with this variable's capabilities, as I usually just use a custom resolution.

[jdmclark]

• ./doc/config.md sounds like a great place for it.
• All config options have default values. The defaults are used whenever a config option is unspecified in the config file.
• data_path has a default of "jkgm".
• log_path can be null or it can be a string (log file path). The default is null.
• max_anisotropy sets the level of anisotropic filtering, but the value's meaning comes directly from ARB_texture_filter_anisotropic. "16x AF" is probably equivalent to setting max_anisotropy to 16.0, so whatever wording seems natural to you is probably fine.
• Setting max_anisotropy to 1.0 will disable anisotropic filtering.
• Regarding internal_resolution, your understanding is correct. It does behave more or less like a custom resolution. It might be worth noting in the doc that you should probably prefer a custom resolution over internal_resolution, where available and convenient.