[doc] Use dollar sign prompt indicator

The hash mark typically represents commands executed in a privileged
environment. Use the dollar sign for normal users, which elevate
privileges with `sudo`.
diff --git a/doc/ug/install_instructions/index.md b/doc/ug/install_instructions/index.md
index f6cd0fd..fd3ae00 100644
--- a/doc/ug/install_instructions/index.md
+++ b/doc/ug/install_instructions/index.md
@@ -267,5 +267,5 @@
 You then need to reload the udev rules:
 
 ```console
-# sudo udevadm control --reload
+$ sudo udevadm control --reload
 ```