add valhalla channel again

Author: VISTALL

hub-shared/src/main/java/consulo/hub/shared/repository/PluginChannel.java

@@ -4,10 +4,12 @@
  * @author VISTALL
  * @since 28-Aug-16
  */
-public enum PluginChannel
-{
-	release, // every month
-	beta,    // every week
-	alpha,   // every day
-	nightly, // every commit
+public enum PluginChannel {
+    release, // every month
+    beta,    // every week
+    alpha,   // every day
+    nightly, // every commit
+    // used for 3-SNAPSHOT - module system, refactoring
+    // used for 4-SNAPSHOT - rewrite lock system
+    valhalla
 }