[#3] Edits to "advanced" document
[#3] Edits to "advanced" document

- Use Markdown for tables
- Mark all class names/constants as code ("``")
- Some editing for flow and to reduce redundant verbiage
- Page level heading; reduced heading levels for subheadings

santiph/apigility-documentation,ezimuel/apigility-documentation,poisa/apigility-documentation,PowerKiKi/apigility-documentation