Add ironfish-wasm build instructions

.gitignore

@@ -11,6 +11,9 @@ testdbs
 # production
 **/build
 
+# rust wasm
+**/pkg
+
 # misc
 .DS_Store
 .env

ironfish-rust-wasm/README.md

@@ -0,0 +1,37 @@
+# Ironfish Rust WASM
+
+This is a WASM build of the Ironfish Rust library.
+
+## Building on Linux
+
+```bash
+wasm-pack build --target web --release
+```
+
+## Building on Mac
+
+### Using `wasm-pack`
+
+Reference: https://mikeder.net/blog/m1-mac-wasm/
+
+```bash
+AR=/opt/homebrew/opt/llvm/bin/llvm-ar CC=/opt/homebrew/opt/llvm/bin/clang wasm-pack build --release --target web
+```
+
+### Using `cargo` and `wasm-bindgen`
+
+In case building with `wasm-pack` fails, you can try building with `cargo` and `wasm-bindgen`:
+
+```bash
+AR=/opt/homebrew/opt/llvm/bin/llvm-ar CC=/opt/homebrew/opt/llvm/bin/clang cargo build --release --target wasm32-unknown-unknown
+```
+
+```bash
+wasm-bindgen ../target/wasm32-unknown-unknown/release/ironfish_wasm.wasm --out-dir ./pkg                          
+```
+
+Install `wasm-bindgen`
+
+```bash
+cargo install -f wasm-bindgen-cli --version 0.2.95
+```