Exa: Document what the color actually means

[Drup]

exa prides itself for providing useful information through colors .... but doesn't actually list what they mean anywhere!

For example, I have literally no idea what underlined yellow is supposed to mean.

[manaskarekar]

I agree that it should be documented, but here's a quick reference.

https://github.com/ogham/exa/blob/master/src/output/colours.rs

[Drup]

That's a list, not a reference nor a documentation. I still have no idea what "immediate" files are. :)

[ogham]

I agree, it's not clear.

[nijikokun]

@Drup for now perhaps these lines will help!

[Drup]

This is ... oddly specific, given the rest of the tool (and ls) only outlines concrete status of elements in the filesystem.

[laughedelic]

Also it's unclear how README (only in caps, readme.md doesn't match) fits this definition:

An “immediate” file is something that can be run or activated somehow
in order to kick off the build of a project. It’s usually only present
in directories full of source code.

I agree with @Drup that this is too specific and I think it's hard to define well and implement. So it will lead more to inconsistencies and users confusion:

"why is my readme in one project is bold yellow and in another it's not? ah, this coloring means that it's an "immediate" file! wait, but then why build.sbt in my Scala project is not highlighted, but the readme is?!"

[majutsushi]

Defining file types like these would be much better done by respecting $LS_COLORS (see #116) than by having a hardcoded list in exa itself.

[thedarkfalcon]

I wondered what the yellow underlining meant, couldn't figure it out so ran _exa --help_ no information there, went to the exa main website.. no information there, so I looked in the release notes.. no information there.. looked on the github project page... no information there.. Thankfully someone made a github issue to ask 😂

[ogham]

Oh, this was #261 too.

I've now added some documentation to the man page that says what the colours mean, how to customise them, and how to turn them off.