[Documentation Improvement]: SIMD Acceleration through WebAssembly Intrinsics doesn't work if you follow instructions in readme

[mcbarton]

Description of issue with documention/Way documentation can be improved

Despite it working in the deployment, if you follow the instructions in the Emscripten build instructions file, the SIMD Acceleration through WebAssembly Intrinsics example doesn't work locally. Unsure what is different between the ci and readme. Will investigate.