[tutorial 020] Group variables inside a family

The "manual" mode structural descriptions are write in a new files to separate things. But Rougail will concatenate variables and families.

We create a family, which will contain other variables.

This family has:

- a description
- a type

As there is no variable inside this family, the type is mandatory. Without it, Rougail will create a variable.

In fact, this family will be deleted by Rougail too because it is empty.

firefox/10-manual.yml

@@ -0,0 +1,8 @@
+%YAML 1.2
+---
+version: 1.1
+
+manual:
+  description: Manual proxy configuration
+  type: family
+...