Following are my observations while verifying the doc, Please modify the doc as mentioned below..

In the Configure Mirroring Section :
https://access.qa.redhat.com/documentation/en/red-hat-ceph-storage/2/block-device-guide/#configuring_mirroring

1.
=> One block device client is connected to each of the clusters: client.master and client.slave. For information on installing Ceph clients, see the Client Installation chapter in the Installation Guide for Red Hat Enterprise Linux. 

 -- the keyring should be in the format "master.client.master.keyring" - with only client.master and client.slave rbd fails with cephx authentication.
We need to create a new cephx authentication.

2.
=> On both client hosts, install the rbd-mirror package:

# yum install rbd-mirror

 -- We have to install "ceph-common" and also copy the admin keyring to the Client host. Please mention about that.
Update the same for Image configuration also

3.
=>  Add the clusters as peers:

$ rbd mirror pool peer add data client.slave@slave --cluster master
$ rbd mirror pool peer add data client.master@master --cluster slave

 -- This section should be moved after enabling the pool mirroring
This fails as the pool needs to be enabled first.
Steps 4 & 5 should to be interchanged both in Pool and Image configurations.


4.
=> Configuring Image Mirroring
On both client hosts, enable and start the rbd-mirror daemon: 

 -- Add one more command to make the daemon start by itself after rebooting
# systemctl enable ceph-rbd-mirror.target


= > The stack pool on the master cluster contains the image1 and image2. Journaling is enabled on the images. See Enabling Journaling for details. 

 -- The name of the pool mentioned in prereq is "stack" but the syntax and examples contains pool name as "data".

Looks good to me..
Moving to Verified state.