Doc++

These aliases are no longer needed as search can handle them properly;
removed superfluous prefix from page name.

doc/openal-support.dox

@@ -27,7 +27,7 @@
 
 namespace Magnum {
 
-/** @page openal-support OpenAL support state
+/** @page openal-support Support state
 @brief List of (un)supported OpenAL features and extensions.
 
 @tableofcontents

doc/opengl-mapping.dox

@@ -28,8 +28,6 @@ namespace Magnum {
 /** @page opengl-mapping Command mapping
 @brief List of OpenGL commands corresponding to particular Magnum API.
 
-@m_keyword{OpenGL command mapping,,}
-
 @tableofcontents
 @m_footernavigation
 

doc/opengl-support.dox

@@ -28,8 +28,6 @@ namespace Magnum {
 /** @page opengl-support Support state
 @brief List of (un)supported OpenGL features and extensions.
 
-@m_keyword{OpenGL support state,,}
-
 @tableofcontents
 @m_footernavigation
 

doc/opengl-workarounds.dox

@@ -27,8 +27,6 @@ namespace Magnum {
 /** @page opengl-workarounds Driver workarounds
 @brief List of OpenGL driver workarounds used by Magnum
 
-@m_keyword{OpenGL driver workarounds,,}
-
 @m_footernavigation
 
 Driver workarounds used by a particular app are listed in the engine startup