message: Properly document how to run tests locally
  ### [Click to see rendered document](https://github.com/swc-project/swc/blob/a9d0617c2978da13eea14720b1d4879dc9382abf/CONTRIBUTING.md#getting-your-development-environment-set-up)
  It's pretty non-trivial and I think it needs to be simplified.
diff: @@ -79,16 +79,33 @@ You can use `rustup component add --toolchain nightly rustfmt-preview` to instal
  After cloning the project there are a few steps required to get the project running.
  -1. `git submodule update --init --recursive` This will pull in the ecmascript test suited
  -2. Go to the folder `ecmascript/transforms` and run `yarn install`
  -3. You need to setup some environment variables in order for the tests to run
  +1. Fetch submodules to pull ECMAScript test suites.
  + ```bash
  + git submodule update --init --recursive
  ```
  -RUST_MIN_STACK=16777216
  -RUSTFLAGS="--cfg procmacro2_semver_exempt"
  +
  +2. Install js dependencies.
  +
  + ```bash
  + yarn add browserslist
  + ( cd ecmascript/transforms; yarn install )
  ```
  -4. You can now run the tests with `RUST_BACKTRACE=full cargo test --color always --all --all-features`
  +3. Setup some environment variables which is required for tests.
  +
  + ```bash
  + export RUST_MIN_STACK=16777216
  + export RUSTFLAGS='--cfg procmacro2_semver_exempt'
  + export RUST_BACKTRACE=full
  + export PATH="$PATH:$PWD/ecmascript/transforms/node_modules/.bin"
  + ```
  +
  +4. Run tests
  +
  + ```bash
  + cargo test --all --all-features
  + ```
  ## Pull requests
  