Update EASTL_Project_Integration.md

[PetiteViking]

Some info for building with CMake was outdated.

• Adding the subdirectory will set up include paths for the packages. No need to do it explicitly.
• Set include directory per target.
• EASTL_LIBRARY is now called EASTL.
• Two new operator overloads are required.

[grojo-ea]

Hello,

Thanks for updating these!

The change looks good to me. Could you please fill out our CLA form with your info so we can merge this change?

[PetiteViking]

Done!