message: Update contributing guide
  Add checkout fork step-by-step guide.
  Add development environment setup guide.
  Add troubleshooting lerna note
diff: @@ -5,6 +5,38 @@ The following is a set of guidelines for contributing to material-ui-pickers. Th
  guidelines is to maintain a high quality of code *and* traceability. Please respect these
  guidelines.
  +
  +## Setting up
  +Please make sure that we are using `develop` branch for active development. So your branches must be created from *develop* and not from the ~~master~~. Here is a short step-by-step guide how to get started
  +
  +1. Fork the material-ui-pickers repository on Github
  +2. Clone your fork to your local machine `git clone git@github.com:<yourname>/material-ui-pickers.git`
  +3. Checkout develop `git checkout develop`
  +4. Create a branch `git checkout -b feature/my-topic-branch`
  +5. Make your changes, lint, run tests, then push to to GitHub with `git push --set-upstream origin my-topic-branch`.
  +6. Visit GitHub and make your pull request.
  +
  +If you have an existing local repository, please update it before you start, to minimise the chance of merge conflicts.
  +```sh
  +git remote add upstream git@github.com:dmtrKovalenko/material-ui-pickers.git
  +git checkout develop
  +git pull upstream develop
  +git checkout -b my-topic-branch
  +```
  +
  +## Dev environment
  +We are using lerna for development environment so it should be enough to make
  +```sh
  +npm install
  +npm start
  +```
  +
  +To start development environment and be sure the `lib` folder is linked properly to the `docs` and your changes will be applied to the docs website. If you faced some problems with symlinking please do the following:
  +```sh
  +npx lerna clean
  +npx lerna bootstrap
  +```
  +
  ## General
  This repository use tests and a linter as automatic tools to maintain the quality of the code.
  These two tasks are run locally on your machine before every commit (as a pre-commit git hook),
  