When trying to follow Administration guide for CRW v2.6 in section: 
3.2. Building custom registry images
at point 8 for the procedure:

8. Build a custom devfile registry image:

$ cd dependencies/che-devfile-registry
$ ./build.sh --organization <my-org> \
 --registry <my-registry> \
 --tag <my-tag> \
 --latest-only

$ cd ../../dependencies/che-devfile-registry
$ ./build.sh --organization <my-org> \
 --registry <my-registry> \
 --tag <my-tag> \
 --latest-only

The --latest-only parameter is not available in the ./build.sh script for git@github.com:redhat-developer/codeready-workspaces.git in crw-2.6-rhel-8 branch

So it should be removed from the documentation by my opinion.
—
Additionally maybe I am missing something but I do not understand why it is there two times, probably it is a bug and should be removed the second build.sh command.