SshHelper: Add class javadoc

Change-Id: I80ab0c2225ad02628b630889c299c474e0087d70
diff --git a/src/main/java/com/googlesource/gerrit/plugins/replication/SshHelper.java b/src/main/java/com/googlesource/gerrit/plugins/replication/SshHelper.java
index 2b16a66..d73c101 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/replication/SshHelper.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/replication/SshHelper.java
@@ -25,6 +25,7 @@
 import org.eclipse.jgit.util.FS;
 import org.eclipse.jgit.util.io.StreamCopyThread;
 
+/** Utility class that provides SSH access to remote URIs. */
 public class SshHelper {
   private final Provider<SshSessionFactory> sshSessionFactoryProvider;
   private final int commandTimeout;