Update README.md

README.md

@@ -131,7 +131,8 @@ Optionally specify following CMake options for custom builds:
 
 * `-DBUILD_SHARED_LIBS=ON` to enable a [shared](https://cmake.org/cmake/help/latest/variable/BUILD_SHARED_LIBS.html) library build,
 * `-DVCPKG=ON` to enable the [vcpkg](https://vcpkg.io) compatible library only build without executables,
-* `-DDEB=ON` to enable the [deb](https://en.wikipedia.org/wiki/Deb_(file_format)) package build for library and main executable.
+* `-DDEB=ON` to enable the [deb](https://en.wikipedia.org/wiki/Deb_(file_format)) package build for library and main executable,
+* `-DWASM=ON` to enable the [wasm](https://emscripten.org) library build used in [demo](https://github.com/jurihock/stftPitchShiftDemo).
 
 ### Python