Add spec for SPV_EXT_shader_invocation_reorder. (#368)

* Add spec for SPV_EXT_shader_invocation_reorder.

* Apply suggestions from code review

Co-authored-by: Daniel Koch <[email protected]>

* Add contributors, fix typos, address review feedback.

* Another typo.

---------

Co-authored-by: Daniel Koch <[email protected]>

Author: alelenv

README.md

@@ -98,6 +98,7 @@ Note: we no longer push the HTML along side the extension.
 * [SPV_EXT_shader_atomic_float_min_max     ]( https://github.khronos.org/SPIRV-Registry/extensions/EXT/SPV_EXT_shader_atomic_float_min_max.html)
 * [SPV_EXT_shader_atomic_float16_add       ]( https://github.khronos.org/SPIRV-Registry/extensions/EXT/SPV_EXT_shader_atomic_float16_add.html)
 * [SPV_EXT_shader_image_int64              ]( https://github.khronos.org/SPIRV-Registry/extensions/EXT/SPV_EXT_shader_image_int64.html)
+* [SPV_EXT_shader_invocation_reorder       ]( https://github.khronos.org/SPIRV-Registry/extensions/EXT/SPV_EXT_shader_invocation_reorder.html)
 * [SPV_EXT_shader_stencil_export           ]( https://github.khronos.org/SPIRV-Registry/extensions/EXT/SPV_EXT_shader_stencil_export.html)
 * [SPV_EXT_shader_tile_image               ]( https://github.khronos.org/SPIRV-Registry/extensions/EXT/SPV_EXT_shader_tile_image.html)
 * [SPV_EXT_shader_viewport_index_layer     ]( https://github.khronos.org/SPIRV-Registry/extensions/EXT/SPV_EXT_shader_viewport_index_layer.html)