doc: Add install guide instructions.

README.md

@@ -95,6 +95,30 @@ or at all:
   overlay on Wayland (layer-shell) and X11. Auto-detects your
   environment.
 
+## Install
+
+See [docs/guides/install.md](docs/guides/install.md) for full details.
+The short version:
+
+```sh
+cargo install pikl
+```
+
+Or from source:
+
+```sh
+git clone https://github.com/maplecool/pikl-menu.git
+cd pikl-menu
+cargo install --path .
+```
+
+## Guides
+
+- **[Install](docs/guides/install.md):** cargo install, building from source
+- **[App Launcher](docs/guides/app-launcher.md):** set up pikl as a
+  keyboard-driven app launcher on Hyprland, i3, macOS (Raycast), or
+  in a terminal
+
 ## Building
 
 ```sh