PMM2 manual page "Updating PMM2 server via Docker"

the manual page for updating PMM2 server via Docker seems a little outdated:

$ docker exec -it pmm-server head -1 /srv/update/main.yml<br># v1.5.3

That command doesn’t work for PMM2, and also doesn’t work with container name “pmm-server2”.
The directory “/srv/update/” seems to be empty.
Is there a command to extract the version from a PMM2 container?
Also, most commands on the page reference “pmm-server” instead of “pmm-server2”, which I believe is the new default name?

That’s an error on our part (I’ll create a Jira to get that page fixed ASAP)! 
pmm-server is whatever you called it at the point of “docker run”…most of our docs stick with pmm-server regardless of version but the command to get the currently running version is clearly wrong as there’s no main.yml in the /srv/update directory inside the container.  
We’ve not yet flipped the tag for percona/pmm-server:latest to reference pmm2 as there are a few items we’d like to get done from a parity standpoint but the soon-to-be released 2.9.0 will have 2 big ones that get us closer to being able to make that switch.  For now to upgrade your container you can use percona/pmm-server:2 tag which will pull the latest image in the 2.x series.  

Hi Steffen,
The information about the currently installed version of PMM Server can be get by an API request.
docker exec -it pmm-server curl -u admin:admin http://localhost/v1/version

Also possible:

docker exec -it pmm-server2 ls -1 "/usr/share/licenses/"|grep pmm-server

But probably more prone to changes than the API call.