DESIGN_KW documentation is unclear

[yngve-sk]

Reading this, and it isn't really clear...

• Exactly what is a template file is and what are some example usages
• It always reads from parameters.txt (this is clear), BUT it is not clear that for all parameters named x, they can be referred to as <x> within the template file, which will be search-and-replace'd
• A simple example referring to <CONFIG_PATH>/template_file showing the input template file and resulting output file