added start of some docs

docs/usage/wasm.md

@@ -0,0 +1,22 @@
+
+# Use mize in a js project
+
+## On the Web
+```bash
+npm init wasm-app project_dir
+cd project_dir
+npm install @c2vi/mize
+```
+
+
+
+## Build npm package yourself
+### with nix
+```bash
+nix build github:c2vi/mize#npmPackage
+```
+
+### without nix
+```bash
+wasm-pack build -- --features wasm-target
+```