doc(#16): installation more obvious

Author: peterpeterparker

doc/slides/slides.md

@@ -345,6 +345,18 @@ The slide "Chart" relies on the charts components `<deckgo-pie-chart/>` and `<de
 
 **Important note**: The [DeckDeckGo] charts components are provided in separate extra library. If you wish to add charts to your presentation, you will need to install this extra component from a CDN or [npm](https://www.npmjs.com/package/deckdeckgo). See the related documentation from its [installation guide](https://github.com/fluster/deckdeckgo-charts#getting-started).
 
+From a CDN:
+
+```
+<script src="https://unpkg.com/deckdeckgo-charts@latest/dist/deckdeckgo-charts.js"></script>
+```
+
+From NPM:
+
+```
+npm install deckdeckgo-charts
+```
+
 The reasons behind are the following:
 
 1. If you don't use charts, you will not have to install unnecessary dependencies