Improvements to docblock descriptions of query template functions

[johnbillion]

The docblock descriptions for the various get_*_template() functions are not very clear, and some are incorrect. The overly verbose descriptions would be better replaced by lists and examples.

Some @since tags are also missing.

[morganestes]

These changes look good to me. It's a lot more clear about how hierarchy works, without having to read through a chart for each type.

Are CPTs handled in the single-{post_type}.php template hierarchy, and if so, should they be specifically mentioned?

[morganestes]

Updated the patch with 38249.diff​ to fix the indentation of the ordered lists in the docs to match the
​Coding Standards for descriptions. Also tweaked the page template hierarchy docs to make it more clear that the first one is the filename, not the template name.

[morganestes]

Ignore 38249.2.diff​ and 38249.3.diff​. They got added during testing of grunt-patch-wordpress and I can't remove them.

[johnbillion]

In 38789:

Themes: Improve the inline documentation for the get_*_template() functions by providing examples instead of verbose explanations.

Fixes #38249
See #37770