GitilesWeblinks: Annotate as @Singleton

Change-Id: I8a7e4d72d5071cdb3efbfba1abe4f98824255979
diff --git a/src/main/java/com/googlesource/gerrit/plugins/gitiles/GitilesWeblinks.java b/src/main/java/com/googlesource/gerrit/plugins/gitiles/GitilesWeblinks.java
index 4ec8a2d..8385f8f 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/gitiles/GitilesWeblinks.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/gitiles/GitilesWeblinks.java
@@ -25,8 +25,10 @@
 import com.google.gerrit.extensions.webui.ProjectWebLink;
 import com.google.gerrit.server.config.PluginConfigFactory;
 import com.google.inject.Inject;
+import com.google.inject.Singleton;
 import org.eclipse.jgit.lib.Config;
 
+@Singleton
 public class GitilesWeblinks
     implements BranchWebLink,
         FileWebLink,