Improve Jinja resources

[tamsinforbes]

This could be split into general Jinja guidance in it's own page on AP User Guidance and guidance specific to create-a-derived-table in its pages with internal links to former.

As an analyst and engineer I need specific examples of what other people have done regarding Jinja resources and writing macros; manuals, example code, tutorials, run logs to look at the compiled Jinja code translated into SQL/Data Definition Language or Data manipulation language so I can check it wrote the SQL code to be run and is what I expected it to do, and examples of how to name macros, where to save them and how to invoke them, pass variables etc.

As User Guidance is public facing perhaps don't want to mention specific names of databases/tables

Should include

• links to Jinja docs
• example code, how to pass variables, other common requirements
• (check the "single use" variable issue 445)
  Specific to create-a-derived-table
• how to find the run logs to see compiled Jinja code
• best practise for naming macros, where to save them, how to invoke them, pass variables