docs: Document new features in radeon/r200/r300 drivers

Signed-off-by: Nicolai Hähnle <nhaehnle@gmail.com>

docs/relnotes-7.6.html

@@ -50,6 +50,8 @@ This was written by Zack Rusin at Tungsten Graphics.
 <li>Rewritten radeon/r200/r300 driver using a buffer manager
 <li>radeon/r200/r300 GL_EXT_framebuffer_object support when used with
     kernel memory manager
+<li>radeon/r200/r300 support for GL_ARB_occlusion_query</li>
+<li>r300 driver supports OpenGL 1.5</li>
 <li>r300 driver support for GL_EXT_vertex_array_bgra, GL_EXT_texture_sRGB
 <li>i915/945 driver support for GL_ARB_point_sprite, GL_EXT_stencil_two_side
     and GL_ATI_separate_stencil extensions