Update Docs for description repository

docs/migration_guide.md

@@ -93,8 +93,7 @@ For any reason, if you want to roll back to the previous version of Harbor, foll
     ```
     docker run -ti --rm -e DB_USR=root -e DB_PWD=xxxx -v /data/database:/var/lib/mysql -v /path/to/backup:/harbor-migration/backup vmware/harbor-db-migrator:[tag] restore
     ```
-    **NOTE:** Rollback from harbor 1.3 to harbor 1.2 must use `vmware/harbor-db-migrator:1.2`. Because of DB engine change.
-
+    **NOTE:** Rollback from harbor 1.3 to harbor 1.2 should delete `/data/database` directory first, then create new database directory `docker-compose up -d && docker-compose stop`. And must use `vmware/harbor-db-migrator:1.2` to restore. Because of DB engine change.
 
 3. Remove current Harbor instance.
     ```

docs/user_guide.md

@@ -15,6 +15,7 @@ This guide walks you through the fundamentals of using Harbor. You'll learn how
   * [Manage self-registration.](#managing-self-registration)
   * [Manage email settings.](#managing-email-settings)
 * [Pull and push images using Docker client.](#pulling-and-pushing-images-using-docker-client)
+* [Add description to repositories](#add-description-to-repositories)
 * [Delete repositories and images.](#deleting-repositories)
 * [Content trust.  ](#content-trust)
 * [Vulnerability scanning via Clair.](#vulnerability-scaning-via-clair)
@@ -248,6 +249,19 @@ $ docker push 10.117.169.182/demo/ubuntu:14.04
 
 **Note: Replace "10.117.169.182" with the IP address or domain name of your Harbor node.**
 
+###  Add description to repositories
+
+After pushing an image, an Information can be added by project admin to describe this repository.
+
+First, go into the repository and select the "Info" tab.
+
+![select info tab](img/select_info_tab.png)
+
+Next, click the "EDIT" button, an textarea will appear and enter description here. Click "SAVE" button to save this information.
+
+![edit info](img/edit_description.png)
+
+
 ###  Deleting repositories  
 
 Repository deletion runs in two steps.