docs: "Comparisons" section should be merged/added to "Builtin Tests"

[alvaroaleman]

Every item described inside Comparisons is a test. However, those items are not included in the test section.

This is quite counterintuitive and should be changed.

[untitaker]

That is not true. "Test" has a special meaning in Jinja.

[alvaroaleman]

I do not agree here. Tests and comparisons may differ in how they are declared, but they have the exact same purpose: Be a test in a conditional statement.

If someone reads the docs and finds one of either tests or comparisons, he or she will be led to believe there are no other conditional statemens available.

[davidism]

I think this was addressed by #665, which added the missing comparison operators as tests.