Correct module name in rmmod example

The rmmod command in the example used a hyphen (hello-5), but
Linux kernel module names conventionally use underscores (hello_5)
to align with C identifier naming rules.

This change corrects the module name to use an underscore, ensuring
the documentation is consistent and avoiding potential confusion for
readers trying to run the command.

Signed-off-by: Chia-Hao Chiu <jordan871130@gmail.com>

Author: Jordymalone

lkmpg.tex

@@ -591,7 +591,7 @@ \subsection{Passing Command Line Arguments to a Module}
 myintarray[1] = -1
 got 2 arguments for myintarray.
 
-$ sudo rmmod hello-5
+$ sudo rmmod hello_5
 $ sudo dmesg -t | tail -1
 Goodbye, world 5