Mention rustup, wasm-pack and cargo-watch installation command

docs/CONTRIBUTING.md

@@ -203,6 +203,14 @@ defined by [rust-toolchain](../rust-toolchain.toml) override file. The `rustup`
 will automatically download the appropriate compiler version along with the
 necessary components.
 
+```bash
+enso$ rustup toolchain install stable                  # Stable toolchain required for the following tools.
+enso$ cargo +stable install wasm-pack --version 0.10.2 # Install the wasm-pack toolkit.
+enso$ cargo +stable install cargo-watch                # To enable ./run watch utility
+```
+
+The previous three steps shall be enough to build the IDE via `./run build --dev`.
+
 ### Getting Set Up (JVM)
 
 In order to properly build the `runtime` component, the JVM running SBT needs to