docs: add contributing.md

contributing.md

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+# Contributing to FingerprintJS Pro SPA integration
+
+## Working with code
+
+We prefer to use [yarn](https://yarnpkg.com/) for installing dependencies and running scripts
+
+Main branch is locked for push, so use branches to make changes and create pull request to review code and merge it in main.
+
+### Development playground
+
+There is no specific playground for this library, but you can develop it with [fingerprintjs-pro-react](https://github.com/fingerprintjs/fingerprintjs-pro-react), just [link package](https://yarnpkg.com/cli/link) with `yarn link`.
+
+❗ Build project before testing integration
+
+### How to build
+Just run:
+```shell
+yarn build
+```
+
+### Code style
+
+The code style is controlled by [ESLint](https://eslint.org/) and [Prettier](https://prettier.io/). Run to check that the code style is ok:
+```shell
+yarn lint
+```
+
+You aren't required to run the check manually, the CI will do it. Run to fix code style mistakes (not all mistakes can be fixed automatically):
+```shell
+yarn lint:fix
+```
+
+### How to test
+Tests located in `__tests__` folder and run by [jest](https://jestjs.io/) in [jsdom](https://github.com/jsdom/jsdom) environment.
+
+To run tests you can use IDE instruments or just run:
+```shell
+yarn test
+```
+
+To check the distributive TypeScript declarations, build the project and run:
+```shell
+yarn test:dts
+```
+
+### How to publish
+- Create new brunch
+- Run `yarn release:(major|minor|patch)` depending on version you need
+- Make PR
+- After merging PR in main, GitHub action will new version to npm