Update Building.md

Author: woess

wasm/docs/contributor/Building.md

@@ -2,10 +2,15 @@
 
 ## Prerequisites
 
+### Required dependencies
+
 - Python 3 (required by `mx`)
-- GIT (to download, update, and locate repositories)
-- JDK 11+
-- emscripten or wasi-sdk for translating C files
+- `git` (to download, update, and locate repositories)
+- [JDK 21+](https://www.oracle.com/java/technologies/downloads/)
+
+### Optional dependencies
+- [WABT (WebAssembly Binary Toolkit)](https://github.com/WebAssembly/wabt) for translating _.wat_ files
+- [Emscripten](https://emscripten.org/docs/getting_started/downloads.html) or [WASI SDK](https://github.com/WebAssembly/wasi-sdk) for translating C files
 
 ## Building
 
@@ -37,7 +42,16 @@ We summarize the basic steps below:
 
 5. Build the project:
     ```bash
-    $ mx --dy /truffle,/compiler build
+    $ mx --dynamicimports /compiler build
     ```
 
 These steps will build the `wasm.jar` file in the `mxbuild/dists/jdk<version>` directory, which contains GraalWasm.
+
+## Testing
+
+To run a _.wasm_ file, you can use the following command:
+    ```bash
+    $ mx --dynamicimports /compiler wasm somefile.wasm
+    ```
+
+For instructions how to run the tests, see [Tests and Benchmarks](TestsAndBenchmarks.md).