Update package_update.md

Author: j-nolasco

messages/package_update.md

@@ -40,11 +40,12 @@ Successfully updated the package. %s
 
 # flags.recommended-version-id.summary
 
-Package version ID that subscribers are notified to install or upgrade to.
+ID of the package version that is installed when subscribers click the Upgrade to Recommended Version option on the Installed Package page of their org.
 
 # flags.recommended-version-id.description
 
-Specify the recommended package version for subscribers to install. Subscribers are notified to install the package version ID that you specify. If the subscribers have a different version of the same package installed, they're notified to upgrade to the recommended version.
+Specify the recommended package version for subscribers to install. If a subscriber has a package version installed in their org that is lower than the version you set, the subscriber sees the Upgrade to Recommended Version option on the Installed Package page. Only released package versions can be set as the recommended version.
+
 
 # flags.skip-ancestor-check.summary