160: include more examples and some explanation on how to use cel

[toumorokoshi]

Users are having difficulty adopting AEP-160. The primary issues include:

• lack of example queries
• some clause that explains that you don't need to use CEL in it's entirety.
• mapping CEL syntax to database queries.
• lack of explanation of how to adopt CEL into your stack (libraries avaiable, etc)

While we have the chance, we probably want to examine this AEP and filtering in general a bit more, and see how we can help resolve these challenges. It could result in friction to adopt the AEPs.