Don't use typewriter font for GL and AL references.

It's fugly.

Doxyfile

@@ -261,8 +261,8 @@ ALIASES                = \
     "requires_gl45=@xrefitem requires-gl45 \"Requires OpenGL 4.5\" \"Functionality requiring OpenGL 4.5\"" \
     "requires_extension=@xrefitem requires-extension \"Requires OpenGL extension\" \"Functionality requiring specific OpenGL extension\"" \
     "requires_gl=@xrefitem requires-gl \"Requires desktop OpenGL\" \"Functionality requiring desktop OpenGL\"" \
-    "extension{2}=<a href=\"https://www.khronos.org/registry/OpenGL/extensions/\1/\1_\2.txt\"><tt>\1_\2</tt></a>" \
-    "extension2{3}=<a href=\"https://www.khronos.org/registry/OpenGL/extensions/\1/\3.txt\"><tt>\1_\2</tt></a>" \
+    "extension{2}=<a href=\"https://www.khronos.org/registry/OpenGL/extensions/\1/\1_\2.txt\">\1_\2</a>" \
+    "extension2{3}=<a href=\"https://www.khronos.org/registry/OpenGL/extensions/\1/\3.txt\">\1_\2</a>" \
     "requires_gles20=@xrefitem requires-gles20 \"Requires OpenGL ES 2.0 / WebGL 1.0\" \"Functionality requiring OpenGL ES 2.0 or WebGL 1.0\"" \
     "requires_gles30=@xrefitem requires-gles30 \"Requires OpenGL ES 3.0\" \"Functionality requiring OpenGL ES 3.0\"" \
     "requires_gles31=@xrefitem requires-gles31 \"Requires OpenGL ES 3.1\" \"Functionality requiring OpenGL ES 3.1\"" \
@@ -270,15 +270,15 @@ ALIASES                = \
     "requires_gles=@xrefitem requires-gles \"Requires OpenGL ES or desktop OpenGL\" \"Functionality requiring OpenGL ES or desktop OpenGL\"" \
     "requires_webgl20=@xrefitem requires-webgl20 \"Requires WebGL 2.0\" \"Functionality requiring WebGL 2.0\"" \
     "requires_webgl_extension=@xrefitem requires-webgl-extension \"Requires WebGL extension\" \"Functionality requiring specific WebGL extension\"" \
-    "webgl_extension{2}=<a href=\"https://www.khronos.org/registry/webgl/extensions/\1_\2/\"><tt>\1_\2</tt></a>" \
+    "webgl_extension{2}=<a href=\"https://www.khronos.org/registry/webgl/extensions/\1_\2/\">\1_\2</a>" \
     "fn_al{1}=`al\1()`" \
     "fn_alc{1}=`alc\1()`" \
     "def_al{1}=`AL_\1`" \
     "def_alc{1}=`ALC_\1`" \
     "requires_al_extension=@xrefitem requires-al-extension \"Requires OpenAL extension\" \"Functionality requiring specific OpenAL extension\"" \
-    "al_extension{2}=<a href=\"http://icculus.org/alextreg/index.php?operation=op_showext&extname=AL_\1_\2\"><tt>AL_\1_\2</tt></a>" \
-    "alc_extension{2}=<a href=\"http://icculus.org/alextreg/index.php?operation=op_showext&extname=ALC_\1_\2\"><tt>ALC_\1_\2</tt></a>" \
-    "experimental=@note This functionality is still experimental and may change in the future without keeping full backwards compatibility."
+    "al_extension{2}=<a href=\"http://icculus.org/alextreg/index.php?operation=op_showext&extname=AL_\1_\2\">AL_\1_\2</a>" \
+    "alc_extension{2}=<a href=\"http://icculus.org/alextreg/index.php?operation=op_showext&extname=ALC_\1_\2\">ALC_\1_\2</a>" \
+    "experimental=@attention This functionality is still experimental and may change in the future without keeping full backwards compatibility."
 
 # This tag can be used to specify a number of word-keyword mappings (TCL only).
 # A mapping has the form "name=value". For example adding "class=itcl::class"