Mention that it's possible to search for OpenGL/OpenAL stuff as well.

Doxyfile-mcss

@@ -91,4 +91,6 @@ HTML_EXTRA_STYLESHEET = \
 
 M_PAGE_FINE_PRINT = "<p>Magnum docs. Part of the <a href="http://magnum.graphics/">Magnum project</a>, copyright © <a href="http://mosra.cz/">Vladimír Vondruš</a> and contributors, 2010&ndash;2018.<br />Generated by <a href="http://doxygen.org/">Doxygen</a> {doxygen_version} and <a href="http://mcss.mosra.cz/">m.css</a>. Contact the team via <a href="https://github.com/mosra/magnum">GitHub</a>, <a href="https://gitter.im/mosra/magnum">Gitter</a>, <a href="mailto:info@magnum.graphics">e-mail</a> or <a href="https://twitter.com/czmosra">Twitter</a>.</p>"
 
+M_SEARCH_HELP = "Search for symbols, directories, files, pages, OpenGL/GLSL and OpenAL APIs. You can omit any prefix from the symbol or file path; adding a <code>:</code> or <code>/</code> suffix lists all members of given symbol or directory. Navigate through the list using <span class="m-label m-dim">&darr;</span> and <span class="m-label m-dim">&uarr;</span>, press <span class="m-label m-dim">Enter</span> to go."
+
 # kate: hl Doxyfile