Add an example of creating the content folder

readme.md

@@ -1,5 +1,14 @@
 My personal guitar chord-book written in [ChordPro](https://www.chordpro.org/).
 
+## Before starting
+
+You have to create your own folder with content. You can use the provided
+`content.example`:
+
+```
+cp -r content.example/ content/
+```
+
 ## Requirements
 
 - `docker`