Add StyledStrings, Faces, and @S_str to NEWS

Author: tecosaur

NEWS.md

@@ -8,6 +8,18 @@ New language features
   difference between `public` and `export` is that `public` names do not become
   available when `using` a package/module. ([#50105])
 * `ScopedValue` implement dynamic scope with inheritance across tasks ([#50958]).
+* A new `AbstractString` type, `StyledString`, is introduced that allows for
+  (arbitrary) regional annotations to be attached to an underlying string. This is
+  very useful for allowing styling information to be encoded separately, and along
+  with `Faces` provides a much more sophisticated approach for styling that
+  `printstyled`. There is also a new `StyledChar` type, that is the equivalent
+  new `AbstractChar` type.
+* The new `Faces` struct serves as a container for text styling information
+  (think typeface), and comes with a framework to provide a convenient,
+  extensible (via `addface!`), and customisable (see `loadfaces!`) approach to
+  styled content.
+* The new `@S_str` string macro provides a convenient way of creating a
+  `StyledString` with various faces or other attributes applied.
 
 Language changes
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