DOC: Add what's new note for TTC loading

Author: QuLogic

doc/release/next_whats_new/ttc_fonts.rst

@@ -0,0 +1,18 @@
+Support for loading TrueType Collection fonts
+---------------------------------------------
+
+TrueType Collection fonts (commonly found as files with a ``.ttc`` extension) are now
+supported. Namely, Matplotlib will include these file extensions in its scan for system
+fonts, and will add all sub-fonts to its list of available fonts (i.e., the list from
+`~.font_manager.get_font_names`).
+
+From most high-level API, this means you should be able to specify the name of any
+sub-font in a collection just as you would any other font. Note that at this time, there
+is no way to specify the entire collection with any sort of automated selection of the
+internal sub-fonts.
+
+In the low-level API, to ensure backwards-compatibility while facilitating this new
+support, a `.FontPath` instance (comprised of a font path and a sub-font index, with
+behaviour similar to a `str`) may be passed to the font management API in place of a
+simple `os.PathLike` path. Any font management API that previously returned a string path
+now returns a `.FontPath` instance instead.