add prerequisites section (resolves #2)

Author: Jeff Fredrickson

Diff for: README.md

@@ -4,6 +4,12 @@ A systemd service to disable the C6 state upon system boot, preventing Ryzen fre
 
 This simply installs `zenstates.py` from [ZenStates-Linux](https://github.com/r4m0n/ZenStates-Linux) and creates a one-shot service based on it.
 
+## Prerequisites
+
+The `zenstates.py` script requires the `msr` kernel module. Ensure that you're either loading the `msr` module at startup or have it compiled into the kernel. If `/dev/cpu/*/msr` exists, then your `msr` module is active.
+
+Refer to your specific distribution and init system to find out how to load kernel modules. For instance, if you're using systemd, refer to `man modules-load.d`.
+
 ## Installation
 
 ```