docs add version checking when using a standalone Gitaly node into troubleshooting
Problem to solve
Standalone Gitaly nodes should be updated along with the GitLab application nodes.
This is to be added to the troubleshooting section in https://docs.gitlab.com/ee/administration/gitaly/#troubleshooting-gitaly
Further details
Using GitLab 12.4 and GitLab 12.0 on a Gitaly standalone host resulted in being unable to delete projects. Updating GitLab on the Gitaly standalone host resolved the issue.
Proposal
Add a specific check to confirm that the version match as part of the troubleshooting steps.