add efibootmgr

Applications/System/efibootmgr.md

@@ -0,0 +1,18 @@
+# [efibootmgr](https://github.com/rhboot/efibootmgr)
+
+| Distribution | Package      |
+| ------------ | ------------ |
+| Arch Linux   | `efibootmgr` |
+| Ubuntu       | `efibootmgr` |
+
+Display current Boot Manager settings:
+
+```sh
+efibootmgr
+```
+
+Delete boot entry 7th:
+
+```sh
+efibootmgr -b 7 -B
+```