5.0 bsc1246422 add third party channels

modules/administration/nav-administration-guide.adoc

@@ -32,6 +32,7 @@ endif::[]
 *** xref:custom-channels.adoc[Custom Channels]
 
 ifeval::[{suma-content} == true]
+*** xref:third-party-channels.adoc[Third-Party Channels]
 *** xref:removing-channels.adoc[Remove Channels]
 endif::[]
 

modules/administration/pages/third-party-channels.adoc

@@ -0,0 +1,31 @@
+[[third-party-channels]]
+= Third-party Channels
+
+{productname} includes the ability to synchronize the content of optional third-party repositories with some of the products that can be managed by it.
+
+Some third-party GPG keys are included by default in the {productname} database, and some are not. 
+For third-party keys that are not included, the relevant keys need to be imported when choosing to synchronize such third-party repositories.
+
+To import a GPG key, use the following command syntax, executing the command on the {productname} host server:
+
+----
+# mgradm gpg add <path-to-gpg-key-file-or-URL>
+----
+
+. Example: Adding a GPG key from a file: 
+
+----
+# mgradm gpg add repomd.xml.key
+----
+
+. Example: Adding a GPG key from a remote repository using a URL:
+
+----
+# mgradm gpg add https://public.dhe.ibm.com/software/server/POWER/Linux/yum/OSS/SLES/15/ppc64le/repodata/repomd.xml.key
+----
+
+To list the keys currently held in the {productname} GPG database, run the following command from inside the server container:
+
+----
+# gpg --homedir /var/lib/spacewalk/gpgdir --list-keys
+----