feat(docs): Add contributing and hacking docs (#17)

# Motivation
Every public Dfinity project MUST have a contributing policy.

# Changes
- Add a contributing policy and a HACKING file to get contributors
started.

# Tests
N/A

Author: bitdivine

CONTRIBUTING.md

@@ -0,0 +1,22 @@
+# Contributing to the Chain Fusion Signer
+
+Thank you for your interest in contributing to the Chain Fusion Signer ❤️
+
+## Contributing code changes
+
+If you want to contribute a feature or bug fix, please **reach out to us first** so that we can discuss feasibility and implementation strategies. You can reach out to us:
+
+- on the [forum]
+- by opening [GitHub issues]
+
+Make sure to read the [README] and [LICENSE] first. For development instructions, see the [HACKING] document.
+
+## Bug reports
+
+We really appreciate bug reports through [GitHub issues].
+
+[GitHub issues]: https://github.com/dfinity/chain-fusion-signer/issues
+[forum]: https://forum.dfinity.org/
+[LICENSE]: LICENSE
+[HACKING]: HACKING.md
+[README]: README.md

HACKING.md

@@ -0,0 +1,20 @@
+# Hacking
+
+This document lists information useful for development and deployment purpose.
+
+## Table of content
+
+- [Demo](#demo)
+
+## Demo
+
+This repository contains the chain fusion signer itself, and also an example application with front end and back end canisters.
+
+To deploy the demo:
+
+```
+dfx start --clean --background
+dfx deploy
+```
+
+You can now visit the frontend in your browser and sign messages!