Add NEWS.md entry for enumerate(::IndexStyle, itr) addition and index…

…ing traits rename (#16378). (#21997)

(cherry picked from commit 18d7af8)

NEWS.md

@@ -396,6 +396,11 @@ Library improvements
  `map(uppercase ∘ hex, 250:255)` is now equivalent to
  `map(x -> uppercase(hex(x)), 250:255)` ([#17155]).
 
+ * `enumerate` now supports the two-argument form `enumerate(::IndexStyle, iterable)`.
+ This form allows specification of the returned indices' style. For example,
+ `enumerate(IndexLinear, iterable)` yields linear indices and
+ `enumerate(IndexCartesian, iterable)` yields cartesian indices ([#16378]).
+
 Compiler/Runtime improvements
 -----------------------------
 
@@ -493,6 +498,11 @@ Deprecated or removed
  For example, `isnumber("123")` should now be expressed `all(isnumber, "123")`
  ([#20342]).
 
+ * A few names related to indexing traits have been changed: `LinearIndexing` and
+ `linearindexing` have been deprecated in favor of `IndexStyle`. `LinearFast` has
+ been deprecated in favor of `IndexLinear`, and `LinearSlow` has been deprecated in
+ favor of `IndexCartesian` ([#16378]).
+
  * The two-argument forms of `map` (`map!(f, A)`) and `asyncmap!` (`asyncmap!(f, A)`)
  have been deprecated in anticipation of future semantic changes ([#19721]).
 
@@ -575,6 +585,7 @@ Command-line option changes
 [#12563]: https://github.com/JuliaLang/julia/issues/12563
 [#15850]: https://github.com/JuliaLang/julia/issues/15850
 [#16213]: https://github.com/JuliaLang/julia/issues/16213
+[#16378]: https://github.com/JuliaLang/julia/issues/16378
 [#16961]: https://github.com/JuliaLang/julia/issues/16961
 [#16984]: https://github.com/JuliaLang/julia/issues/16984
 [#16986]: https://github.com/JuliaLang/julia/issues/16986