Add details about repositories to prerequisites (#4428)

Add details about repositories to Smart Proxy upgrade prerequisites

Since the smartproxies can be upgraded separately, some users might miss out on the information about which repos are to be synced.
Adding a prerequisite to ensure this information is not skipped.

JIRA:
https://issues.redhat.com/browse/SAT-37314
Specifically this comment:
https://issues.redhat.com/browse/SAT-37314?focusedId=27987597&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-27987597

Author: AkshayGadhaveRH

guides/common/modules/proc_upgrading-smartproxy-server.adoc

@@ -24,8 +24,9 @@ ifdef::katello,orcharhino[]
 * If you use content views to control updates to the base operating system of {SmartProxyServer}, ensure these content views are up-to-date with the new repositories.
 endif::[]
 ifdef::satellite[]
-* If the {SmartProxyServer} is registered to a content view, add the {SmartProxy} {ProjectVersion} repositories to the content view.
+* Ensure that you synchronize the required repositories on {ProjectServer}.
 For more information, see xref:synchronizing_the_new_repositories_{context}[].
+* If the {SmartProxyServer} is registered to a content view, add the {SmartProxy} {ProjectVersion} repositories to the content view.
 endif::[]
 ifdef::katello,orcharhino,satellite[]
 Publish and promote a new version of the content view.