Add EE checkout instructions to update docs

doc/update/6.0-to-6.1.md

@@ -30,8 +30,9 @@ sudo -u git -H bundle exec rake gitlab:backup:create RAILS_ENV=production
 ```bash
 cd /home/git/gitlab
-sudo -u git -H git fetch
+sudo -u git -H git fetch --all
 sudo -u git -H git checkout 6-1-stable
+# For GitLab Enterprise Edition: sudo -u git -H git checkout 6-1-stable-ee
 ```
 ### 3. Update gitlab-shell

doc/update/6.0-to-6.4.md

@@ -27,8 +27,9 @@ sudo -u git -H bundle exec rake gitlab:backup:create RAILS_ENV=production
 ```bash
 cd /home/git/gitlab
-sudo -u git -H git fetch
+sudo -u git -H git fetch --all
 sudo -u git -H git checkout 6-4-stable
+# For GitLab Enterprise Edition: sudo -u git -H git checkout 6-4-stable-ee
 ```

doc/update/6.1-to-6.2.md

@@ -23,8 +23,9 @@ sudo -u git -H bundle exec rake gitlab:backup:create RAILS_ENV=production
 ```bash
 cd /home/git/gitlab
-sudo -u git -H git fetch
+sudo -u git -H git fetch --all
 sudo -u git -H git checkout 6-2-stable # Latest version of 6-2-stable addresses CVE-2013-4489
+# For GitLab Enterprise Edition: sudo -u git -H git checkout 6-2-stable-ee
 ```
 ### 3. Update gitlab-shell

doc/update/6.2-to-6.3.md

@@ -20,8 +20,9 @@ sudo -u git -H bundle exec rake gitlab:backup:create RAILS_ENV=production
 ```bash
 cd /home/git/gitlab
-sudo -u git -H git fetch
+sudo -u git -H git fetch --all
 sudo -u git -H git checkout 6-3-stable
+# For GitLab Enterprise Edition: sudo -u git -H git checkout 6-3-stable-ee
 ```
 ### 3. Update gitlab-shell (and its config)

doc/update/6.3-to-6.4.md

@@ -15,8 +15,9 @@ sudo -u git -H bundle exec rake gitlab:backup:create RAILS_ENV=production
 ```bash
 cd /home/git/gitlab
-sudo -u git -H git fetch
+sudo -u git -H git fetch --all
 sudo -u git -H git checkout 6-4-stable
+# For GitLab Enterprise Edition: sudo -u git -H git checkout 6-4-stable-ee
 ```
 ### 3. Update gitlab-shell (and its config)