chore: Migrate README to markdown (spinnaker#7906)

README.md

@@ -0,0 +1,66 @@
+# Spinnaker UI
+
+![Deck CI](https://github.com/spinnaker/deck/workflows/Deck%20CI/badge.svg)
+
+## Prerequisites
+
+Make sure that [node](http://nodejs.org/download/) and [yarn](https://yarnpkg.com/en/docs/install) are installed on your system.
+The minimum versions for each are listed in package.json.
+
+## Quick Start
+
+Run the following commands (in the deck directory) to get all dependencies installed in deck and to start the server:
+
+- `yarn`
+- `yarn start`
+
+The app will start up on localhost:9000.
+
+## Environment variables
+
+Environment variables can be used to configure application behavior. The following lists those variables and their possible values:
+
+- `AUTH` enable/disable authentication (default is disabled, enable by setting `AUTH=enabled`).
+- `TIMEZONE` set the default timezone (default is 'America/Los_Angeles' - see http://momentjs.com/timezone/docs/#/data-utilities/ for options)
+- `DECK_CERT` enable SSL (set to the fully qualified path to cert file, and `DECK_KEY` must be set to the fully qualified path to the key file)
+
+The following external resources can be specified with environment variables:
+
+- `API_HOST` overrides the default Spinnaker API host.
+- `AUTH_ENABLED` determines whether Deck will attempt to authenticate users via Gate.
+
+For example, `API_HOST=http://spinnaker.prod.netflix.net yarn start` will run Deck with `http://spinnaker.prod.netflix.net` as the API host.
+
+## Testing
+
+To run the tests within the application, run `yarn test`.
+
+Developing things locally? You may want to run [gate](https://github.com/spinnaker/gate) locally (which runs on port 8084) as well.
+Gate is the service that hosts the spinnaker REST API.
+Then run deck like this:
+
+```
+API_HOST=http://localhost:8084 yarn start
+```
+
+## Building & Deploying
+
+To build the application, run `yarn build`.
+The built application lives in `build/`.
+
+## Conventions
+
+It's a work in progress, but please try to follow the [conventions here](https://github.com/spinnaker/deck/wiki/Conventions).
+
+## Customizing the UI
+
+It's certainly doable - we're in the middle of some significant changes to our build process, which should make it easier.
+For now, you can look at the [all modules](https://github.com/spinnaker/deck/tree/master/app/scripts/modules/) to
+get an idea how we are customizing Deck internally. Expect a lot of this to change, though, as we figure out better, cleaner
+hooks and integration points. And we're happy to provide new integration points (or accept pull requests) following
+those existing conventions if you need an integration point that doesn't already exist.
+
+## Join Us
+
+Interested in sharing feedback on Spinnaker's UI or contributing to Deck?
+Please join us at the [Spinnaker UI SIG](https://github.com/spinnaker/governance/tree/master/sig-ui-ux)!