Removed reference to deprecated poller-service.py (librenms#11598)

* Removed reference to deprecated poller-service.py

* Update Dispatcher-Service.md

Co-authored-by: Tony Murray <[email protected]>

doc/Extensions/Dispatcher-Service.md

@@ -5,21 +5,9 @@ path: blob/master/doc/
 
 > Status: Release Candidate
 
-The new LibreNMS dispatcher service (`librenms-service.py`) replaces
-the old poller service (`poller-service.py`), improving its
-reliability. It's mostly a drop in replacement for the old service,
-but testing is recommended before switching over.
-
-If you are currently using the old poller service, it's strongly
-recommended that you migrate away - it has a serious defect under
-certain versions of mysql/mariadb, and may be inadvertently DoS'ing
-your devices. The new service does not have this issue,
-
-Make sure you uninstall the old poller service before deploying the new service.
-
-The dispatcher does not replace the php scripts, but the cron entries
-running them.  It attempts to do a better job than simple time based
-scheduling.
+The LibreNMS dispatcher service (`librenms-service.py`) is a new method
+of running the poller service at set times. It does not replace the php scripts, 
+just the cron entries running them.
 
 # External Requirements
 
@@ -33,7 +21,7 @@ behaviour only found in Python3.4+.
 - PyMySQL is recommended as it requires no C compiler to
   install. MySQLclient can also be used, but does require compilation.
 - python-dotenv .env loader
-- redis-py 3.0+ and Redis 5.0+ (if using distributed polling)
+- redis-py 3.0+ and Redis 5.0+ server (if using distributed polling)
 
 These can be obtained from your OS package manager, or from PyPI with the below commands.
 
@@ -71,6 +59,7 @@ connections and other important health metrics.
 
 Connection settings are required in `.env`. The `.env` file is
 generated after composer install and APP_KEY and NODE_ID are set.
+Remember that the APP_KEY value must be the same on all your pollers.
 
 ```dotenv
 #APP_KEY=   #Required, generated by composer install
@@ -213,7 +202,7 @@ Then install and configure the runtime and service:
 # vi /etc/redis.conf
 # systemctl enable --now redis.service
 # scl enable rh-python36 bash
-# pip install pymysql redis
+# pip3 install -r requirements.txt
 # cp /opt/librenms/misc/librenms.service.scl /etc/systemd/system/librenms.service
 # systemctl enable --now librenms.service
 ```