Prefer using raw identifiers over display name parameters for tests and suites.

[iamleeg]

Fixes #894.

Describes naming types and functions with readable names, instead of overriding their names with macro parameters.

Motivation:

People use the display name parameters to @Test and @Suite to override the names of their test functions and suites with readable display names. That's still possible, but it's more direct to give things readable names in the first place, so let's explain how to do that.

Modifications:

Documentation changes to demonstrate naming things with raw identifiers.
Hints in the @Suite and @Test documentation to prefer raw identifiers over changing display names.

Checklist:

• Code and documentation should follow the style of the Style Guide.
• If public symbols are renamed or modified, DocC references should be updated.