Add command to install quickly

add in a command which will do all of the installation steps at once.

README.md

@@ -42,6 +42,13 @@ cd yay
 makepkg -si
 ```
 
+If you want to do all of this at once, we can chain the commands like so:
+
+```sh
+pacman -S --needed git base-devel && git clone https://aur.archlinux.org/yay.git && cd yay && makepkg -si
+```
+
+
 ### Binary
 
 If you do not want to compile yay yourself you can use the builds generated by