[wasm] [docs] Improve build flags information
diff --git a/docs/wasm-shaper.md b/docs/wasm-shaper.md
index 91f8b97..5572a4e 100644
--- a/docs/wasm-shaper.md
+++ b/docs/wasm-shaper.md
@@ -370,9 +370,22 @@
## Enabling the WASM shaper when building Harfbuzz
-First, you will need the `wasm-micro-runtime` library installed on your computer. Download `wasm-micro-runtime` from [its GitHub repository](https://github.com/bytecodealliance/wasm-micro-runtime/tree/main); then follow [the instructions for building](https://github.com/bytecodealliance/wasm-micro-runtime/blob/main/product-mini/README.md) (you may want to enable "fast JIT"), followed by a `make install`.
+First, you will need the `wasm-micro-runtime` library installed on your computer. Download `wasm-micro-runtime` from [its GitHub repository](https://github.com/bytecodealliance/wasm-micro-runtime/tree/main); then follow [the instructions for building](https://github.com/bytecodealliance/wasm-micro-runtime/blob/main/product-mini/README.md), except add the `-DWAMR_BUILD_REF_TYPES=1` flag to the `cmake` line. (You may want to enable "fast JIT".) Follow this with a `make install`.
-To enable the WASM shaper, add the string `-Dwasm=enabled` to your meson build line. For example:
+So, for example:
+
+```
+$ cd product-mini/platforms/darwin
+$ mkdir build
+$ cd build
+$ cmake .. -DWAMR_BUILD_REF_TYPES=1 -DWAMR_BUILD_FAST_JIT=1
+$ make
+$ make install
+```
+
+(If you don't want to install `wasm-micro-runtime` globally, you can copy `libiwasm.*` and `libvmlib.a` into a directory that your compiler can see when building Harfbuzz.)
+
+Once `wasm-micro-runtime` is installed, to enable the WASM shaper, you need to add the string `-Dwasm=enabled` to your meson build line. For example:
```
$ meson setup build -Dwasm=enabled
