Added Contributing guide

CONTRIBUTING.md

@@ -0,0 +1,29 @@
+# How to contribute
+
+## Creating an Issue
+
+Before you create a new Issue:
+
+1. Please make sure there is no open issue about the topic yet
+2. If it is a bug report, include the steps to reproduce the issue
+3. If it is a feature request, please share the motivation for the new feature and how you would implement it
+
+## Tests
+
+If you want to submit a bug fix or new feature, make sure that all tests are passing.
+
+```bash
+$ npm test
+```
+
+## Submitting a Pull Request
+
+- Check out the open issues first. Create new ones or discuss if needed
+- Fork the project
+- Push changes to a dedicated branch of your fork
+- Submit a pull request
+- Be sure to tag any issues your pull request is taking care of or is contributing to.
+
+## Development environment
+
+In addition to the classic (npm/node, installation, etc), make sure to define the OBSIDIAN_VAULT_LOCATION environment variable. It should point to the root folder of an existing Obsidian vault. When building the DEV version (`npm run build:dev` or `npm run watch`), the plugin will be copied to that vault's `.obsidian/plugins` folder. This makes it easy to build and automatically have the up to date plugin for testing in Obsidian. It also avoids having to store the codebase within the Obsidian vault...