website: add mention of consul-migrate

website/source/docs/upgrade-specific.html.markdown

@@ -14,6 +14,23 @@ details provided for their upgrades as a result of new features or changed
 behavior. This page is used to document those details seperately from the
 standard upgrade flow.
 
+## Consul 0.5.1
+
+Consul version 0.5.1 uses a different backend store for persisting the Raft
+log. Because of this change, a data migration is necessary to move the log
+entries out of LMDB and into the newer backend, BoltDB.
+
+Consul version 0.5.1 makes this transition seamless and easy. As a user, there
+are no special steps you need to take. When Consul 0.5.1 starts, it checks
+for presence of the legacy LMDB data files, and migrates them automatically
+if any are found.
+
+The automatic upgrade will only exist in Consul 0.5.1. In later versions
+(0.6.0+), the migration code will not be included in the Consul binary. It
+is still possible to upgrade directly from pre-0.5.1 versions by using the
+consul-migrate utility, which is available on the
+[Consul Tools page](/downloads_tools.html).
+
 ## Consul 0.5
 
 Consul version 0.5 adds two features that complicate the upgrade process:

website/source/downloads_tools.html.erb

@@ -29,6 +29,9 @@ description: |-
       <li>
         <a href="https://github.com/hashicorp/consul-template">Consul Template</a> - Generic template rendering and notifications with Consul
       </li>
+      <li>
+        <a href="https://github.com/hashicorp/consul-migrate">Consul Migrate</a> - Data migration tool to handle Consul upgrades to 0.5.1+
+      </li>
     </ul>
   </div>