Add some notes in the blocker FAQ about unsupported repos

case RE-158: Hopefully this reduces the amount of issue filings on that.
Phrasing reviewed by Katherine Frain in DOCS-261.

docs-website-src/content/blockers.md

@@ -149,3 +149,22 @@ These issues with the YUM repositories can cause ELevate to block your upgrade:
   * If YUM is in an unstable state (running `yum makecache` fails).
 
 If any unfinished yum transactions are detected, ELevate will attempt to complete them by executing `/usr/sbin/yum-complete-transaction --cleanup-only`. If this fails, ELevate will block you from beginning the upgrade process until you manually resolve any outstanding issues or transactions.
+
+#### Unsupported Repository
+
+If you receive the following error message when you use this script,
+you have installed packages from an unsupported repository:
+
+One or more enabled YUM repo[sitories] are currently unsupported and have installed packages.
+You should disable these repositories and remove packages installed from them before continuing the update.
+
+We will not allow upgrades while you are using packages from unsupported repositories for the following reasons:
+
+* We cannot be sure that unsupported repositories provides packages for your upgraded distribution version.
+* Even if an unsupported repository provides packages for your upgraded distribution version, we cannot
+be sure installing them will not interfere with your upgrade process.
+
+To upgrade your distribution version, you must first disable these repositories and remove their packages.
+Then, when the upgrade completes, you can reenable and reinstall, or install equivalent packages
+from other repositories. If no equivalent packages exist, you may have to find a different solution
+to provide the package's functionality.

elevate-cpanel

@@ -5433,7 +5433,7 @@ EOS
             }
             if ( $status_hr->{'USE_RPMS_FROM_UNVETTED_REPO'} ) {
                 $msg .= <<~'EOS';
-            One or more enabled YUM repo are currently unsupported and have installed packages.
+            One or more enabled YUM repositories are currently unsupported and have installed packages.
             You should disable these repositories and remove packages installed from them
             before continuing the update.
             EOS

lib/Elevate/Components/Repositories.pm

@@ -164,7 +164,7 @@ sub _blocker_invalid_yum_repos ($self) {
         }
         if ( $status_hr->{'USE_RPMS_FROM_UNVETTED_REPO'} ) {
             $msg .= <<~'EOS';
-            One or more enabled YUM repo are currently unsupported and have installed packages.
+            One or more enabled YUM repositories are currently unsupported and have installed packages.
             You should disable these repositories and remove packages installed from them
             before continuing the update.
             EOS