update readme

Author: mjain-jump

README.md

@@ -20,7 +20,11 @@ Supported APIs:
 
 Install dependencies:
 ```sh
+# For Ubuntu:
 apt install libudev-dev pkg-config
+# For RHEL:
+sudo dnf install -y systemd-devel
+
 git submodule update --init --recursive
 ./deps.sh
 ```