Mention IOSApplicationConfiguration#hdpiMode in gdx 1.9.12 changelog

Author: crykn

_posts/2020/2020-10-31-gdx_1_9_12.md

@@ -33,6 +33,8 @@ One of the major additions in libGDX 1.9.12 is the support for Linux ARM builds
 Version 1.9.12 contains a few breaking changes, which require the developers to take some steps to update their apps:
 
 - The handling of HDPI, ahem, Retina on iOS was adapted to match the implementations on the other platforms ([#3709](https://github.com/libgdx/libgdx/pull/3709)). If you were using `getWidth()` until now, you have to replace those calls with `getBackBufferWidth()` (the same for height). If you rely on viewports, there is no need of changes, because sizes are virtual anyway. If you are using `getDensity()` to position your UI elements, take a look [here](https://github.com/libgdx/libgdx/pull/6263).
+  In libGDX 1.10.0 you can disable this behaviour by setting `IOSApplicationConfiguration#hdpiMode` to `HdpiMode.Pixels`.
+  {: .notice--primary .no-top-margin }
 - `InputProcessor#scrolled` now receives two (!) float (!) values: `scrollX` and `scrollY` ([#6154](https://github.com/libgdx/libgdx/pull/6154)). `InputEvent` was changed accordingly. To match the old behaviour use the `amountY` argument.
 - `Vector2#angleRad(Vector2)` now correctly returns counter-clockwise angles ([#5428](https://github.com/libgdx/libgdx/pull/5428)).
 - Android: `Gdx.graphics.getDeltaTime()` now returns the raw delta time instead of a smoothed one ([#6228](https://github.com/libgdx/libgdx/pull/6228)).