docs: Update `precise` qualifier status in GL3.txt

Signed-off-by: Chris Forbes <chrisf@ijw.co.nz>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>

docs/GL3.txt

@@ -101,7 +101,7 @@ GL 4.0:
   GL_ARB_draw_buffers_blend                            DONE (i965, nv50, nvc0, r600, radeonsi, softpipe)
   GL_ARB_draw_indirect                                 DONE (i965)
   GL_ARB_gpu_shader5                                   started
-  - 'precise' qualifier                                not started
+  - 'precise' qualifier                                DONE
   - Dynamically uniform sampler array indices          not started
   - Dynamically uniform UBO array indices              not started
   - Implicit signed -> unsigned conversions            not started