feat: add a more practical example course

exampleSite/content/courses/example/visualization.md

@@ -0,0 +1,32 @@
+---
+title: Visualization
+date: '2021-01-01'
+type: book
+weight: 30
+highlight: true
+---
+
+Learn how to visualize data with Plotly.
+
+<!--more-->
+
+{{< icon name="clock" pack="fas" >}} 1-2 hours per week, for 8 weeks
+
+## Learn
+
+{{< youtube hSPmj7mK6ng >}}
+
+## Quiz
+
+{{< spoiler text="When is a heatmap useful?" >}}
+Lorem ipsum dolor sit amet, consectetur adipiscing elit.
+{{< /spoiler >}}
+
+{{< spoiler text="Write Plotly code to render a bar chart" >}}
+```python
+import plotly.express as px
+data_canada = px.data.gapminder().query("country == 'Canada'")
+fig = px.bar(data_canada, x='year', y='pop')
+fig.show()
+```
+{{< /spoiler >}}