Added Shader Compiler's default defines to the docs (#2911)
Added Shader Compiler's default defines to the docs (#2911)

* Added shaderc default defines to docs

* Update tools.rst

* Update tools.rst

Co-authored-by: Бранимир Караџић <a51d32610a255449bd8868a3bbd33941625e0ee1@gmail.com>
LWJGL-CI/bgfx,bkaradzic/bgfx,LWJGL-CI/bgfx,bkaradzic/bgfx,bkaradzic/bgfx,LWJGL-CI/bgfx,bkaradzic/bgfx,LWJGL-CI/bgfx