add installation README

README.md

@@ -1,3 +1,43 @@
 # Nola GRUB Theme
 
-![Nola Grub](./preview.jpg)
+![Nola Grub](./preview.jpg)
+
+# Installation
+
+Create grub themes folder (if not exist)
+
+```bash
+sudo mkdir -p /boot/grub/themes
+```
+
+Clone this repo:
+
+```bash
+git clone --depth 1 https://gitea.nonszy.space/nomi-nonsz/nola-grub.git
+```
+
+Copy the theme
+
+```bash
+sudo cp nola-grub /boot/grub/themes/nola-grub
+```
+
+Change the theme in `/etc/default/bash`
+
+```ini
+GRUB_THEME="/boot/grub/themes/nola-grub/theme-txt"
+```
+
+### Applying configuration
+
+On Debian/Ubuntu based distro:
+
+```
+sudo update-grub
+```
+
+Or other distro:
+
+```
+sudo grub-mkconfig -o /boot/grub/grub.cfg
+```