docs: added local install notes

docs/install/local.md

@@ -1,3 +1,20 @@
 # Local install
 
-Local installation with Node.js
+The local method uses the [Node.js](https://nodejs.org/en) installation found on your system.
+
+## Requirements
+
+- **Node 20** or later
+- [pnpm](https://pnpm.io/installation)
+
+## Install
+
+```bash
+git clone -b dev/0.15.0 https://github.com/tycrek/ass.git && cd ass/
+pnpm i
+# or: npm i -D
+pnpm run dev
+
+# After ass has been compiled, you can instead use:
+pnpm run start
+```