Move startup_commands.txt.example to startup_commands.txt for consistency with the existing shutdown_commands.txt.

Add comments to both files saying what they are (files that can contain console commands to execute on sim startup/shutdown) with an example.

bin/shutdown_commands.txt

@@ -1,2 +1,3 @@
 ; You can place simulator console commands here to execute when the simulator is shut down
 ; e.g. show stats
+; Lines starting with ; are comments

bin/startup_commands.txt

@@ -0,0 +1,3 @@
+; You can place region console commands here to execute once the simulator has finished starting up 
+; e.g. show stats
+; Lines start with ; are comments.

bin/startup_commands.txt.example

@@ -1,4 +0,0 @@
-terrain load-tile f32 islandterrain_1024x512.raw 512 1024 1000 1000
-terrain multiply 0.1
-terrain add 5
-