Revamped content and layout of project docs (README, CONTRIBUTING, etc) (#2770)

* Moved "optional" project documentation files to docs/ subdir to minimise clutter in project root.

* Verbatim copy of Contributor Covenant v2.1. Updated code of conduct contact details, removing anyone who don't list obvious contact details (@lyzidiamond and @tcql).

* Split publishing topic out into a separate document. Only a small subset of contributors will ever publish so better to have CONTRIBUTING focus on coding and PR related activities.

* Updated issue and PR templates to read a bit better, ask for more meaningful details.

* Updating open collective stats, project goals for coming year.

* Split readme into a few pieces. Cut a lot of cut and paste commands (hard to guarantee currency). Removed REGEN references - think it's use should be discouraged, though probably differing opinions on that one!

Co-authored-by: mfedderly <[email protected]>
Co-authored-by: Tim Welch <[email protected]>

---------

Co-authored-by: mfedderly <[email protected]>
Co-authored-by: Tim Welch <[email protected]>

Author: 3 people

.github/ISSUE_TEMPLATE.md

@@ -1,9 +1,10 @@
 Please provide the following when reporting an issue:
 
-- [ ] The version of Turf you are using, and any other relevant versions.
-- [ ] GeoJSON data as a [gist file](https://gist.github.com/) or [geojson.io](http://geojson.io/) (filename extension must be `.geojson`).
-- [ ] Snippet of source code or for complex examples use [jsfiddle](https://jsfiddle.net/).
-- [ ] Verify this issue hasn't already been reported, or resolved in the latest alpha pre-release.
+- [ ] Description of the problem, and how it differs from what you expected.
+- [ ] Version of Turf you are using, and of any other relevant software.
+- [ ] GeoJSON data as a [gist file](https://gist.github.com/) or [geojson.io](https://geojson.io/) (filename extension must be `.geojson`). Simple reproducible examples are preferrable.
+- [ ] Snippet of source code for complex examples using [jsfiddle](https://jsfiddle.net/).
+- [ ] Confirmation this issue hasn't already been reported, or is resolved and just hasn't been released yet.
 
 <!-- Love turf? Please consider supporting our collective:
 👉  https://opencollective.com/turf/donate -->

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,11 +1,8 @@
-Please fill in this template. Use a meaningful title for the pull request. Include the name of the package modified.
+Please provide the following when creating a PR:
 
-- [ ] Is this a bug fix, new functionality, or a breaking change?
-- [ ] Have read and followed the steps for [preparing a pull request](https://github.com/Turfjs/turf/blob/master/CONTRIBUTING.md#preparing-a-pull-request).
-
-Submitting a new TurfJS Module.
-
-- [ ] Overview description of proposed module.
-- [ ] Include JSDocs with a basic example.
-- [ ] Execute `./scripts/generate-readmes` to create `README.md`.
-- [ ] Add yourself to **contributors** in `package.json` using "Full Name <@GitHub Username>".
+- [ ] Meaningful title, including the name of the package being modified.
+- [ ] Summary of the changes.
+- [ ] Heads up if this is a breaking change.
+- [ ] Any issues this [resolves](https://docs.github.com/en/get-started/writing-on-github/working-with-advanced-formatting/using-keywords-in-issues-and-pull-requests).
+- [ ] Inclusion of your details in the `contributors` field of `package.json` - you've earned it! 👏
+- [ ] Confirmation you've read the steps for [preparing a pull request](https://github.com/Turfjs/turf/blob/master/docs/CONTRIBUTING.md#preparing-a-pull-request).