Fix wasm build instructions #1336

Job	Run time
emscripten_wasm (ubu24, ubuntu-24.04, 3.1.45, bash)	2m 53s
build (ubu24, ubuntu-24.04, bash)	1m 23s
emscripten_wasm (ubu22, ubuntu-22.04, 3.1.45, bash)	2m 53s
build (ubu24-analyzers, ubuntu-24.04, true, -DCMAKE_BUILD_TYPE=Debug, bash)	2m 12s
emscripten_wasm (osx13-x86, macos-13, 3.1.45, bash)	4m 22s
build (ubu22, ubuntu-22.04, bash)	1m 25s
emscripten_wasm (osx14-arm, macos-14, 3.1.45, bash)	2m 47s
build (osx13-x86, macos-13, bash)	4m 3s
emscripten_wasm (osx15-arm, macos-15, 3.1.45, bash)	2m 59s
build (osx14-arm, macos-14, bash)	1m 10s
build (osx15-arm, macos-15, bash)	1m 13s
build (Windows22, windows-2022, cmd.exe)	3m 55s
build (Windows25, windows-2025, cmd.exe)	2m 23s
	33m 38s

Provide feedback