Add @return docs for interleave_changed_lines() (and prevent bad parsing)

[coffee2code]

For interleave_changed_lines() in WP_Text_Diff_Renderer_Table, the return value is documented rather sparsely and poorly in the description and not documented in @return except as being an array. (In fact, it is slightly better documented in a comment preceding its sole invocation, in _changed().)

This existing documentation utilizes a glob-style notation that fails to accurately indicate the exact return value array elements to be expected. Additionally, this unnecessary notation gets misinterpreted as Markdown by WP-Parser, resulting in a mangled description for the function in developer.wordpress.org (appearing as partially italicized text and a stray text in a code block).

See: ​https://developer.wordpress.org/reference/classes/wp_text_diff_renderer_table/interleave_changed_lines/
(or for posterity: 38520.bad-parsing.png​)

Attached is a patch (38520.diff​) to add documentation of the proper syntax and with better docs themselves.

[coffee2code]

Screenshot of DevHub showing bad parsing of function description due to poor syntax use

[coffee2code]

Patch referenced in ticket (w/ whitespace fixes from original patch)

[DrewAPicture]

In 40971:

Docs: Add full parameter and return documentation for WP_Text_Diff_Renderer_Table::interleave_changed_lines().

Props coffee2code.
Fixes #38520.