Improve utility documentation even more.

src/Magnum/Audio/al-info.cpp

@@ -48,6 +48,9 @@ find_package(Magnum REQUIRED al-info)
 add_custom_command(OUTPUT ... COMMAND Magnum::al-info ...)
 @endcode
 
+See @ref building, @ref cmake and the @ref Audio namespace for more
+information.
+
 @section magnum-al-info-usage Usage
 
 @code{.sh}

src/Magnum/Platform/gl-info.cpp

@@ -98,6 +98,8 @@ find_package(Magnum REQUIRED gl-info)
 add_custom_command(OUTPUT ... COMMAND Magnum::gl-info ...)
 @endcode
 
+See @ref building, @ref cmake and the @ref GL namespace for more information.
+
 @section magnum-gl-info-usage Usage
 
 @code{.sh}

src/Magnum/Text/fontconverter.cpp

@@ -73,6 +73,8 @@ find_package(Magnum REQUIRED fontconverter)
 add_custom_command(OUTPUT ... COMMAND Magnum::fontconverter ...)
 @endcode
 
+See @ref building, @ref cmake and the @ref Text namespace for more information.
+
 @section magnum-fontconverter-usage Usage
 
 @code{.sh}

src/Magnum/TextureTools/distancefieldconverter.cpp

@@ -79,6 +79,9 @@ find_package(Magnum REQUIRED distancefieldconverter)
 add_custom_command(OUTPUT ... COMMAND Magnum::distancefieldconverter ...)
 @endcode
 
+See @ref building, @ref cmake and the @ref TextureTools namespace for more
+information.
+
 @section magnum-distancefieldconverter-usage Usage
 
 @code{.sh}

src/Magnum/Trade/imageconverter.cpp

@@ -50,6 +50,9 @@ find_package(Magnum REQUIRED imageconverter)
 add_custom_command(OUTPUT ... COMMAND Magnum::imageconverter ...)
 @endcode
 
+See @ref building, @ref cmake and the @ref Trade namespace for more
+information.
+
 @section magnum-imageconverter-usage Usage
 
 @code{.sh}