* Add example of templating inline using copy module
The **copy** module documentation implies that `content:` only works
for 'simple values' and for complex stuff you need the **template**
module, but that is an understatement. You can use **copy** to template
anything you desire.
So I changed the wording, added an example, and also added a note
to the template module that the **copy** module could be used for
'inline templating'.
This fixes#19741.
be1c517f4d