Add prettier hook & contribution guide (#105)

CONTRIBUTING.md

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+# Contributing
+
+Dyad is still a very early-stage project, thus the codebase is rapidly changing.
+
+Before opening a pull request, please open an issue and discuss whether the change makes sense in Dyad. Ensuring a cohesive user experience sometimes means we can't include every possible feature or we need to consider the long-term design of how we want to support a feature area.
+
+## More than code contributions
+
+Something that I really appreciate are all the non-code contributions, such as reporting bugs, writing feature requests and participating on [Dyad's sub-reddit](https://www.reddit.com/r/dyadbuilders).
+
+## Development
+
+Dyad is an Electron app.
+
+**Install dependencies:**
+
+```sh
+npm install
+```
+
+**Run locally:**
+
+```sh
+npm start
+```