simplify and rework docs

For new contributors unfamiliar with GHD dev process, the absolute minimum info I'de expect to find in any project of this complexity.

We got rid of contributors MD, so IMO the additions would have made my life easier in the beggining.

** Theres room for improvement as with all things.

Notes:

Indtead of adding remap-css short how to into readme I added to header of mappings.js it can be further broken down to make clear what things do.

README.md

@@ -100,30 +100,36 @@
 
 [1]:https://github.com/StylishThemes/GitHub-Dark/pull/568
 
-## Notes
+## Contributions and Development
 
-- If you're using a custom domain for GitHub Enterprise, be sure to include it through a `@-moz-document` rule (Firefox) or add it to the `Applies to` section in (Chrome).
+If you would like to contribute to this repository, please...
 
-## Contributions
+1. [![fork](https://user-images.githubusercontent.com/136959/42383736-c4cb0db8-80fd-11e8-91ca-12bae108bccc.png) Fork](https://github.com/StylishThemes/GitHub-Dark/fork)
+1. Make sure you have these installed:
 
-If you would like to contribute to this repository, please...
+- [`node`](https://nodejs.org): version 12 or greater
+- [`yarn`](https://classic.yarnpkg.com/en/docs/install/): version 1
+- `make`: available with UNIX-like OS, on Windows you can use [this](https://stackoverflow.com/a/54086635/808699)
 
-1. 👓 Read the [contribution guidelines](./CONTRIBUTING.md).
-1. [![fork](https://user-images.githubusercontent.com/136959/42383736-c4cb0db8-80fd-11e8-91ca-12bae108bccc.png) Fork](https://github.com/StylishThemes/GitHub-Dark/fork) or [![cloud-download](https://user-images.githubusercontent.com/136959/42401932-9ee9cae0-813d-11e8-8691-16e29a85d3b9.png) download](https://github.com/StylishThemes/GitHub-Dark/archive/master.zip) this repository.
-1. 👌 Create a pull request!
+Then run `make deps` to install dependencies.
 
-## Development
+### Auto generated CSS
 
-First, make sure you have these installed:
+Contributing e.g unstyled items, sources, extensions, etc. to name a few.
 
-- [`node`](https://nodejs.org): version 12 or greater
-- [`yarn`](https://classic.yarnpkg.com/en/docs/install/): version 1
-- A Unix-like environment with `make` (on Windows use [this](https://stackoverflow.com/a/54086635/808699))
+See and edit the respective files in [/src/gen/](./src/gen/).
+
+And then run `make build install` to rebuild the style and install it test you fixes and PR back.
+
+### Manual override entries
 
-Edit the files in [`src`](./src) and then run `make build install` to rebuild the style and install it.
+Manual overrides to e.g. generated content or inline HTML styles to name a few;
+
+See and edit respective files in [`src`](./src) and then run `make build install` to rebuild and install the style, to test you fixes and PR back.
 
 ### Make Targets
 
+- `make deps`: Install development dependencies into `Github Dark/node_modules`
 - `make build`: Build `github-dark.user.css`
 - `make install`: Install `github-dark.user.css`
 - `make lint`: Run linters
@@ -133,9 +139,18 @@ Lesser used targets include:
 
 - `make authors`: Regenerate the `AUTHORS` file based on git history
 - `make update`: Update dependencies
+- `make`: Alias for `make build`
+
+Internal use only targets include:
+
 - `make patch`: Increment the patch version, create a commit and push it
 - `make minor`: Increment the minor version, create a commit and push it
 - `make major`: Increment the major version, create a commit and push it
-- `make`: Alias for `make build`
 
-Thanks to all that have [contributed](./AUTHORS) so far! And thanks for the shoutout on the [JS Party](https://changelog.com/jsparty/20#transcript-71) podcast!
+## Notes
+
+- If you're using a custom domain for GitHub Enterprise, be sure to include it through a `@-moz-document` rule (Firefox) or add it to the `Applies to` section in (Chrome). See
+
+- Any additions into `github-dark.user.css` are lost on `make build`
+
+Thanks to all our [contributors](./AUTHORS) so far! And thanks for the shoutout on the [JS Party](https://changelog.com/jsparty/20#transcript-71) podcast!

src/gen/mappings.js

@@ -1,4 +1,12 @@
 module.exports.mappings = {
+  // ==========================================================================
+  //                         Short How-to
+  // `$border: value`: Any occurance of `value` in a `border` property.
+  // `$background: value` Any occurance of `value` in a `background` property.
+  // `$box-shadow: value` Any occurance of `value` in a `box-shadow` property.
+  // `$color: value`: Any occurance of `value`.
+  // `color | fill | background | etc: value`: Any occurance of `value` in a `color | fill | background | etc` property.
+  //
   // ==========================================================================
   // Color anywhere
   // ==========================================================================