doc: updated credits and changelog.

doc/changelog.dox

@@ -710,8 +710,9 @@ See also:
 -   Added a note about MinGW GCC and Clang ABI incompatibility to
     @ref platforms-windows "Windows platform docs" (see [mosra/magnum#227](https://github.com/mosra/magnum/issues/227) and
     [mosra/magnum#439](https://github.com/mosra/magnum/issues/439))
--   Various documentation fixes (see [mosra/magnum#492](https://github.com/mosra/magnum/issues/492))
+-   Various documentation fixes (see [mosra/magnum#492](https://github.com/mosra/magnum/issues/492),
--   @ref Corrade::Utility::Debug and friends were always brought to the )
+    [mosra/magnum#521](https://github.com/mosra/magnum/pull/521))
+-   @ref Corrade::Utility::Debug and friends were always brought to the
     @ref Magnum namespace via a @cpp using @ce directive, but this was never
     reflected in the docs and thus hidden from users. Now it's shown in the
     docs as a set of @ref Debug etc typedefs instead, to make them more

doc/credits.dox

@@ -82,7 +82,7 @@ Are the below lists missing your name or something's wrong?
 [Let us know!](https://magnum.graphics/contact/)
 
 -   **Aaron Gokaslan** ([\@Skylion007](https://github.com/Skylion007)) ---
-    various minor code modernization
+    various minor code modernization, typo fixes
 -   **[\@abgita](https://github.com/abgita)** --- minor typo fixes
 -   **Alan Jefferson** ([\@alanjfs](https://github.com/alanjfs)) --- extensive
     usability and first-time-use feedback