Cleanup some clustering rough edges

Summary: Suppress an unhelpful Almanac transaction and document the location of the secret clustering management capability. I thought maybe implementing `shouldHide` and checking for `isCreate` would work, but the binding apparently gets created before an interface is bound to it.

Test Plan: Looked at a fresh binding and didn't see "Unknown Object(??)", ran bin/diviner and saw expected output.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Differential Revision: https://secure.phabricator.com/D19917

src/applications/almanac/xaction/AlmanacBindingInterfaceTransaction.php

@@ -55,11 +55,22 @@ final class AlmanacBindingInterfaceTransaction
   }
 
   public function getTitle() {
-    return pht(
-      '%s changed the interface for this binding from %s to %s.',
-      $this->renderAuthor(),
-      $this->renderOldHandle(),
-      $this->renderNewHandle());
+    if ($this->getOldValue() === null) {
+      return pht(
+        '%s set the interface for this binding to %s.',
+        $this->renderAuthor(),
+        $this->renderNewHandle());
+    } else if ($this->getNewValue() == null) {
+      return pht(
+        '%s removed the interface for this binding.',
+        $this->renderAuthor());
+    } else {
+      return pht(
+        '%s changed the interface for this binding from %s to %s.',
+        $this->renderAuthor(),
+        $this->renderOldHandle(),
+        $this->renderNewHandle());
+    }
   }
 
   public function validateTransactions($object, array $xactions) {

src/docs/user/cluster/cluster_repositories.diviner

@@ -98,7 +98,7 @@ repository to retrieve the data it needs. It will use the result of this query
 to respond to the user.
 
 
-Setting up a Cluster Services
+Setting up Cluster Services
 =============================
 
 To set up clustering, first register the devices that you want to use as part
@@ -107,6 +107,17 @@ of the cluster with Almanac. For details, see @{article:Cluster: Devices}.
 NOTE: Once you create a service, new repositories will immediately allocate
 on it. You may want to disable repository creation during initial setup.
 
+NOTE: To create clustered services, your account must have the "Can Manage
+Cluster Services" capability. By default, no accounts have this capability,
+and you must enable it by changing the configuration of the Almanac
+application. Navigate to the Alamanc application configuration as follows:
+{nav icon=home, name=Home >
+Applications >
+Almanac >
+Configure >
+Edit Policies >
+Can Manage Cluster Services }
+
 Once the hosts are registered as devices, you can create a new service in
 Almanac: