Added `advligorts` group and user instructions for "Install advligorts packages, Setup RCG", "Option B"

Post-Install-Setup.md

@@ -29,7 +29,7 @@ Run the following:
 apt-get update
 ```
 
-All  sources should load without error.  
+All sources should load without error.  
 
 If there are any packages that need updating, update with
 
@@ -41,16 +41,14 @@ apt-get dist-upgrade
 
 Log into the new front end as root. At the command line, type the following as root:
 
-
-## Rocky
-
+**For Rocky Linux**
 ```plaintext
 groupadd -g 1001 controls
 useradd -u 1001 -s /bin/bash -m -g controls controls
 passwd controls
 ```
 
-## Debian (bullseye, Debian 11)
+**For Debian** (last tested on bullseye, Debian 11)
 ```plaintext
 /usr/sbin/addgroup --gid 1001 controls
 /usr/sbin/adduser --uid 1001 --shell /bin/bash --ingroup controls controls
@@ -170,7 +168,21 @@ Now clone the repo
 ```plaintext
 controls@x2fec /opt/rtcds/rtscore $ git clone https://git.ligo.org/cds/advligorts
 controls@x2fec /opt/rtcds/rtscore $ ln -s advligorts release
+
+Add the `advligorts` user and group.
+
+**For Rocky Linux**
+```plaintext
+groupadd advligorts
+useradd -s /bin/bash -g advligorts advligorts
 ```
+
+**For Debian** (last tested on bullseye, Debian 11)
+```plaintext
+/usr/sbin/addgroup advligorts
+/usr/sbin/adduser --no-create-home --shell /bin/bash --ingroup advligorts advligorts
+```
+
 # Setup Environment variables
 ## lowercase vars