Improve the #include behaviour description.
Improve the #include behaviour description.

dneto0/shaderc,antiagainst/shaderc,dneto0/shaderc,fuchsia-mirror/third_party-shaderc,dneto0/shaderc,fuchsia-mirror/third_party-shaderc,antiagainst/shaderc,antiagainst/shaderc,fuchsia-mirror/third_party-shaderc,antiagainst/shaderc,dneto0/shaderc