doc: updated credits and changelog.

doc/changelog.dox

@@ -476,6 +476,8 @@ See also:
 -   Worked around a regression in MSVC 2017 causing a compiler crash (see
     [mosra/magnum#440](https://github.com/mosra/magnum/issues/440))
 -   Linker fixes for MinGW Clang (see [mosra/magnum#417](https://github.com/mosra/magnum/pull/417))
+-   Properly installing plugin binaries in Gentoo packages (see
+    [mosra/magnum-plugins#85](https://github.com/mosra/magnum-plugins/issues/85))
 
 @subsection changelog-latest-bugfixes Bug fixes
 

doc/credits.dox

@@ -92,6 +92,8 @@ Are the below lists missing your name or something's wrong?
     --- Multi-channel support in the @ref Audio library, standard conformance;
     float, double, A-Law and μ-Law format support in the
     @ref Audio::WavImporter "WavAudioImporter" plugin
+-   **Andrew ([\@sheerluck](https://github.com/sheerluck)) --- Gentoo package
+    fixes
 -   **Andy Somogyi** ([\@andysomogyi](https://github.com/andysomogyi)) ---
     bugreports, API design improvement suggestions
 -   **[\@ArEnSc](https://github.com/ArEnSc)** --- initial implementation of