Add nix-on-droid as an Android installation method (coder#6196)

Author: henkery

docs/android.md

@@ -21,3 +21,11 @@ nvm use 16
 8. Install code-server globally on device with: `npm install --global code-server --unsafe-perm`
 9. Run code-server with `code-server`
 10. Access on localhost:8080 in your browser
+
+# Running code-server using Nix-on-Droid
+
+1. Install Nix-on-Droid from [F-Droid](https://f-droid.org/packages/com.termux.nix/)
+2. Start app
+3. Spawn a shell with code-server by running `nix-shell -p code-server`
+4. Run code-server with `code-server`
+5. Access on localhost:8080 in your browser