message: Add dev environment setup instructions
diff: @@ -75,6 +75,20 @@ You can use `rustup component add --toolchain nightly rustfmt-preview` to instal
  `rustfmt +nightly --unstable-features --skip-children` on the changed files to automatically format your code.
  * Push your commits to GitHub and create a pull request against swc's `master` branch.
  +## Getting your development environment set up
  +
  +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
  +
  +```
  +RUST_MIN_STACK=16777216
  +RUSTFLAGS="--cfg procmacro2_semver_exempt"
  +```
  +
  +4. You can now run the tests with `RUST_BACKTRACE=full cargo test --color always --all --all-features`
  ## Pull requests
  