doc: MSYS2 packages are now in the official repo.

doc/building.dox

@@ -195,10 +195,16 @@ There are also ArchLinux packages for @ref building-plugins-packages-arch "Magnu
 
 @subsection building-packages-msys MSYS2 packages
 
-`PKGBUILD`s for [MSYS2](https://www.msys2.org/) are in the `package/msys`
+[MSYS2](https://www.msys2.org/) package for the latest stable release is
-directory. Similarly to ArchLinux, there is one package in the
+mantained in the official repos. Installing is as simple as this:
-`package/msys/magnum` directory, which will download and package latest stable
+
-release; and then a development `PKGBUILD`, allowing you to package and install
+@code{.sh}
+pacman -S mingw-w64-x86_64-magnum # or mingw-w64-i686-magnum
+@endcode
+
+Similarly to ArchLinux, there is one package in the `package/msys/magnum`
+directory, which will download and package latest stable release; and then a
+development `PKGBUILD` in `package/msys`, allowing you to package and install
 the currently checked out source tree. Both depend on a corresponding
 @ref building-corrade-packages-msys "Corrade MSYS2 package". Example usage:
 

doc/changelog.dox

@@ -180,6 +180,8 @@ See also:
 
 @subsection changelog-latest-buildsystem Build system
 
+-   @ref building-packages-msys "MSYS2 packages" are now in official
+    repositories, installable directly via `pacman`
 -   Updated *extremely* outdated Emscripten boilerplate from the
     [base-emscripten bootstrap project](https://github.com/mosra/magnum-bootstrap/tree/base-emscripten)
     (the HTML markup was unchanged since 2013, heh)