Define and apply standard formatting

[Larocceau]

While trying to find an example for writing a new recipe, I came across a few different formats for recipes.

• Some recipes include a H1 title, some don't
• some recipes include a short introduction, some don't
• Some skip certain header sizes
• Some templates include code diffs, most don't

I'd also say it would be a good idea to include the version of the template the recipe was tested on as a standard element of the recipe

Proposed actions:

• Determine a standard for layouts, and document this in contributing.md
• apply the defined layout to existing templates