Update Active Record's attribute query methods documentation to describe its full behaviour. [ci skip]
Clarify that the word present refers to Object#present?. [ci skip]

Update Active Record's attribute query methods documentation to clarify that whether an attribute is present is based on Object#present?. This gives people a place to go see what the exact definition of presence is. [ci skip]
Clarify that query methods have a custom definition of whether a numeric value is present. [ci skip]

The way Active Record query methods handle numeric values is a special case, and is not part of Rails's standard definition of present. This update attempts to make this more clear in the docs, so that people don't expect Object#present? to return false if used on a number that is zero.
Merge pull request #18159 from M7/docs-active_record-update_query_method_docs_with_full_description

Describe full behaviour of Active Record's attribute query methods