docs: add CONTRIBUTING.md (#1745)

* add CONTRIBUTING

* remove dev stuff from readme

* update release checklist from wiki

* fix hierarchy

* add docker info

* respond to nate's comments

CONTRIBUTING.md

@@ -0,0 +1,101 @@
+# Contributing
+
+## Set up your dev environment
+
+We use Node v14 for development - that is the version that our linters require.
+
+To set up the repository:
+1. Clone the repository
+2. `cd` into the repository
+3. Install dependencies with `npm install`
+
+To build the library:
+```bash
+npm run build
+```
+
+## Run the linter
+
+```bash
+npm install
+npm run lint
+```
+
+## Running Tests
+
+For integration and browser tests, we use a `rippled` node in standalone mode to test xrpl.js code against. To set this up, you can either run `rippled` locally, or set up the Docker container `natenichols/rippled-standalone:latest` for this purpose. The latter will require you to [install Docker](https://docs.docker.com/get-docker/).
+
+### Unit Tests
+
+```bash
+npm install
+npm test
+```
+
+### Integration Tests
+
+```bash
+npm install
+# sets up the rippled standalone Docker container - you can skip this step if you already have it set up
+docker run -p 6006:6006 -it natenichols/rippled-standalone:latest
+npm run test:integration
+```
+
+### Browser Tests
+
+There are two ways to run browser tests.
+
+One is in the browser - run `npm run build:browserTests` and open `test/localIntegrationRunner.html` in your browser.
+
+The other is in the command line (this is what we use for CI) -
+
+```bash
+npm run build:browserTests
+# sets up the rippled standalone Docker container - you can skip this step if you already have it set up
+docker run -p 6006:6006 -it natenichols/rippled-standalone:latest
+npm run test:browser
+```
+
+## Generate reference docs
+
+You can see the complete reference documentation at [`xrpl.js` docs](js.xrpl.org). You can also generate them locally using `typedoc`:
+
+```bash
+npm run docgen
+```
+
+## Release process
+
+### Editing the Code
+
+* Your changes should have unit and/or integration tests.
+* Your changes should pass the linter.
+* Your code should pass all the tests on Github (which check the linter, unit and integration tests on Node 12/14/16, and browser tests).
+* Open a PR against `develop` and ensure that all CI passes.
+* Get a full code review from one of the maintainers.
+* Merge your changes.
+
+### Release
+
+1. Ensure that all tests passed on the last CI that ran on `develop`.
+2. Open a PR to update the docs if docs were modified.
+3. Create a branch off `develop` that properly increments the version in `package.json` and ensures that `HISTORY.md` is updated appropriately. We follow [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+  * Use `shasum -a 256 build/*` to get the SHA-256 checksums. Add these to `HISTORY.md` as well.
+4. Merge this branch into `develop`.
+5. If this is not a beta release: Merge `develop` into `master` (`--ff-only`) and push to github. This is important because we have docs telling developers to use master to get the latest release.
+6. Create a new Github release/tag off of this branch.
+7. Run `npm publish --dry-run` and make sure everything looks good.
+8. Publish the release to `npm`.
+  * If this is a beta release, run `npm publish --tag beta`. This allows someone else to install this version of the package with `npm install xrpl@beta`.
+  * If this is a stable release, run `npm publish`.
+  * This will require entering `npm` login info.
+9. Send an email to [xrpl-announce](https://groups.google.com/g/xrpl-announce).
+
+## Mailing Lists
+We have a low-traffic mailing list for announcements of new `xrpl.js` releases. (About 1 email every couple of weeks)
+
++ [Subscribe to xrpl-announce](https://groups.google.com/g/xrpl-announce)
+
+If you're using the XRP Ledger in production, you should run a [rippled server](https://github.com/ripple/rippled) and subscribe to the ripple-server mailing list as well.
+
++ [Subscribe to ripple-server](https://groups.google.com/g/ripple-server)