improved message

roles/set_semaphore_count/README.md

-Some program, i.e. GAMESS, needs a larger number of system semaphores than normal.
-This program creates a systemd file that sets the value on startup, so that it is persistent
+Some programs, i.e. GAMESS, needs a larger number of system semaphores than  provided by default.
+This role creates a systemd file that sets the value on startup, so that it is persistent after reboot
 
-To set count:
+Shell command to set count: This is the default value for the role
 echo 500 256000 64 10240 > /proc/sys/kernel/sem
 
 We use a variable SEM_COUNT so users can override the default setting.
 
 use
-- { role: set_semaphore_count } #to use default value
-
+- { role: set_semaphore_count } #to use default value hardcoded inside main.yml, (as above)
+or
 - { role: set_semaphore_count, SEM_COUNT: "200 252000 24 20240" } #to use some other value (the ones here are nonsense for example only)