Add systemd-boot timeout til

linux/systemd-boot-timeout.md

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+# Change systemd-boot timeout
+
+<https://wiki.archlinux.org/title/systemd-boot>
+
+The loader configuration is stored in the file `*esp*/loader/loader.conf`. See [loader.conf(5) § OPTIONS](https://man.archlinux.org/man/loader.conf.5#OPTIONS) for details.
+
+A loader configuration example is provided below:
+
+*esp*/loader/loader.conf
+
+default  arch.conf
+timeout  4
+console-mode max
+editor   no
+
+**Tip:**
+
+- systemd-boot does not accept tabs for indentation, use spaces instead.
+- `default` and `timeout` can be changed in the boot menu itself and changes will be stored as UEFI variables `LoaderEntryDefault` and `LoaderConfigTimeout`, overriding these options.
+- `bootctl set-default ""` and `bootctl set-timeout ""` can be used to clear the UEFI variables overriding the `default` and `timeout` options, respectively.
+- If you have set `timeout 0`, the boot menu can be accessed by pressing `Space`.
+- A basic loader configuration file is located at `/usr/share/systemd/bootctl/loader.conf`.
+- If the bootloader (during the entry selection) appears distorted/uses the wrong resolution you can try to set the `console-mode` to `auto` (uses heuristics to select the best resolution), `keep` (keeps the firmware provided resolution) or `2` (tries to select the first non-UEFI-standard resolution).