cbbackupmgr backup of user and user groups with --enable-users

Due to a regression issue, the cbbackupmgr backup/restore of users and user groups is no longer being done by default.  Instead, the backup of users and groups will be an opt-in using the option --enable-users .

Also, you must be a Full Admin to be able to backup/restore users/user groups using the option --enable-users .

When restoring users/user groups, the existing users and groups will not be restored unless the option to overwrite users and groups ( --overwrite-users ) is used.

Note:  This affects these pages that had been updated for DOC-11199.

• modules/backup-restore/pages/enterprise-backup-restore.adoc 
• modules/introduction/partials/new-features-76.adoc

Note:  The following pages will also need to be updated:

https://docs-staging.couchbase.com/server/7.6/backup-restore/cbbackupmgr-config.html

https://docs-staging.couchbase.com/server/7.6/backup-restore/cbbackupmgr-restore.html