message: Add link to register to slack.
diff: ### [harp.gl site](https://heremaps.github.io/harp.gl/)
  -### [harp.gl Slack channel](https://heredev.slack.com/messages/harpgl/)
  +### [harp.gl Slack channel](https://heredev.slack.com/messages/harpgl/) Registration available [here](http://t.her.is/slack).
  ## Overview
  @@ -27,20 +27,29 @@ that can display a map using our default style. You can get results like the one
  You can consume the harp.gl api with two different methods:
  -* linking a simple bundle as a `<script>` tag in your html
  -* installing a set of node modules from npm
  +- linking a simple bundle as a `<script>` tag in your html
  +- installing a set of node modules from npm
  If you want to learn more about the applications you can create, please check the [Getting Started Guide](docs/GettingStartedGuide.md).
  ### Simple bundle
  Add `three.js` and `harp.gl` to your html and create a canvas with an id `map`:
  +
  ```html
  <html>
  <head>
  <style>
  - body, html { border: 0; margin: 0; padding: 0; }
  - #map { height: 100vh; width: 100vw; }
  + body,
  + html {
  + border: 0;
  + margin: 0;
  + padding: 0;
  + }
  + #map {
  + height: 100vh;
  + width: 100vw;
  + }
  </style>
  <script src="https://unpkg.com/three/build/three.min.js"></script>
  <script src="https://unpkg.com/@here/harp.gl/dist/harp.js"></script>
  @@ -51,11 +60,14 @@ Add `three.js` and `harp.gl` to your html and create a canvas with an id `map`:
  </body>
  </html>
  ```
  +
  Initialize the map:
  +
  ```javascript
  const map = new harp.MapView({
  canvas: document.getElementById("map"),
  - theme: "https://unpkg.com/@here/harp-map-theme@latest/resources/berlin_tilezen_night_reduced.json",
  + theme:
  + "https://unpkg.com/@here/harp-map-theme@latest/resources/berlin_tilezen_night_reduced.json"
  });
  const controls = new harp.MapControls(map);
  const omvDataSource = new harp.OmvDataSource({
  @@ -175,7 +187,7 @@ have to establish baseline:
  Performance test steps
  -1) Establish baseline results.
  +1. Establish baseline results.
  ```
  $ git checkout master
  @@ -186,15 +198,15 @@ PROFILEHELPER_COMMAND=baseline yarn performance-test-node # create baseline of m
  > have to write new dedicated performance test for code that is about to be optimized.
  > See `tests/performance` for examples.
  -2) Go back to your branch, change stuff and
  +2. Go back to your branch, change stuff and
  -3) Rerun tests with your changes
  +3. Rerun tests with your changes
  ```
  yarn performance-test-node --grep lines # assuming you're playing with lines
  ```
  -4) Examine output:
  +4. Examine output:
  ```
  ...
  @@ -205,7 +217,6 @@ performance createLineGeometry segments=2
  gcTime=39.6195ms (-3.39% vs 41.011ms) sumNoGc=959.54ms (0.15% vs 958.11ms) throughputNoGc=520633.00/s (-6.61% vs 557461.83/s)
  ```
  -
  ### Generate documentation
  Run:
  