docs/relnotes: add the EGL Device extensions

Signed-off-by: Emil Velikov <emil.velikov@collabora.com>

docs/relnotes/18.3.0.html

@@ -63,6 +63,9 @@ Note: some of the new features are only available with certain drivers.
 <li>GL_KHR_texture_compression_astc_sliced_3d on radeonsi.</li>
 <li>GL_INTEL_fragment_shader_ordering on i965.</li>
 <li>GL_NV_fragment_shader_interlock on i965.</li>
+<li>EGL_EXT_device_base for all drivers.</li>
+<li>EGL_EXT_device_drm for all drivers.</li>
+<li>EGL_MESA_device_software for all drivers.</li>
 </ul>
 
 <h2>Bug fixes</h2>