Add `ONOS` to dictionary and fix usage in text blocks

Change-Id: I9eabdacfcff34c8e730c0148e1e6ce078cff796a
diff --git a/advanced/connectivity/external-connectivity.rst b/advanced/connectivity/external-connectivity.rst
index c8b1612..618ddf3 100644
--- a/advanced/connectivity/external-connectivity.rst
+++ b/advanced/connectivity/external-connectivity.rst
@@ -187,7 +187,7 @@
     fpm connection ip 10.6.0.1 port 2620
     !
 
-The FPM connection IP address is the IP address of **one of the onos cluster
+The FPM connection IP address is the IP address of **one of the ONOS cluster
 instances** - does not matter which one.  If you have other configuration that
 needs to go in ``zebra.conf`` you should add that here as well.
 
diff --git a/dict.txt b/dict.txt
index 8d2eddd..1f90758 100644
--- a/dict.txt
+++ b/dict.txt
@@ -21,6 +21,7 @@
 NxM
 ONF
 ONIE
+ONOS
 OpenConfig
 PFCP
 Pre
diff --git a/troubleshooting.rst b/troubleshooting.rst
index 6c0d74e..fdc0764 100644
--- a/troubleshooting.rst
+++ b/troubleshooting.rst
@@ -59,7 +59,7 @@
 ..
     TODO Hung-Wei
 
-onos-diagnostics
+ONOS diagnostics
 ----------------
 ..
     TODO Hung-Wei