docs: update README.md for clarity

* Removed the period at the end of the description for the LinuxGSM image.
* Enhances consistency in the documentation style.

Author: dgibbs64

README.md

@@ -1,6 +1,6 @@
 # LinuxGSM Base Docker Image
 
-## This is the base LinuxGSM image only.
+## This is the base LinuxGSM image only
 
 ## Use <a href="https://github.com/GameServerManagers/docker-gameserver">docker-gameserver</a> for full game servers