Merge branch 'backup_gitlab.com' into 'master'

Added note about backups for gitlab.com

Added note about backups for Gitlab.com based on question on Twitter
https://twitter.com/MarcelloLins/status/598544357294272513

See merge request !1828

doc/raketasks/backup_restore.md

@@ -299,3 +299,7 @@ Example: LVM snapshots + rsync
 
 If you are running GitLab on a virtualized server you can possibly also create VM snapshots of the entire GitLab server.
 It is not uncommon however for a VM snapshot to require you to power down the server, so this approach is probably of limited practical use.
+
+### Note
+This documentation is for GitLab CE. 
+We backup GitLab.com and make sure your data is secure, but you can't use these methods to export / backup your data yourself from GitLab.com.
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