docs: Mark ARB_shader_storage_buffer_object as in progress

Reviewed-by: Chris Forbes <chrisf@ijw.co.nz>
diff --git a/docs/GL3.txt b/docs/GL3.txt
index 9d56ee5..44a824b 100644
--- a/docs/GL3.txt
+++ b/docs/GL3.txt
@@ -164,7 +164,7 @@
   GL_ARB_program_interface_query                       DONE (all drivers)
   GL_ARB_robust_buffer_access_behavior                 not started
   GL_ARB_shader_image_size                             in progress (Martin Peres)
-  GL_ARB_shader_storage_buffer_object                  not started
+  GL_ARB_shader_storage_buffer_object                  in progress (Iago Toral, Samuel Iglesias)
   GL_ARB_stencil_texturing                             DONE (i965/gen8+, nv50, nvc0, r600, radeonsi, llvmpipe, softpipe)
   GL_ARB_texture_buffer_range                          DONE (nv50, nvc0, i965, r600, radeonsi, llvmpipe)
   GL_ARB_texture_query_levels                          DONE (all drivers that support GLSL 1.30)
@@ -221,7 +221,7 @@
   GL_ARB_shader_atomic_counters                        DONE (i965)
   GL_ARB_shader_image_load_store                       in progress (curro)
   GL_ARB_shader_image_size                             in progress (Martin Peres)
-  GL_ARB_shader_storage_buffer_object                  not started
+  GL_ARB_shader_storage_buffer_object                  in progress (Iago Toral, Samuel Iglesias)
   GL_ARB_shading_language_packing                      DONE (all drivers)
   GL_ARB_separate_shader_objects                       DONE (all drivers)
   GL_ARB_stencil_texturing                             DONE (i965/gen8+, nv50, nvc0, r600, radeonsi, llvmpipe, softpipe)