Improve the UX of 'copy to clipboard' button on registry page

Today, during a discussion at slack (https://gitlab.slack.com/archives/C0SFP840G/p1525244331000245), we've concluded that the 'copy to clipboard' UX is not user friendly.

When using the copy to clipboard button, user most probably will expect, that he'll copy the name of the image. But instead a docker pull name_of_the_image is copied. This ends with a funny, but painful easy to overlook bugs like: gitlab-org/security-products/tests/java-maven@5875fe81:

- name: registry.gitlab.com/gitlab-org/security-products/analyzers/find-sec-bugs:latest
+ name: docker pull registry.gitlab.com/gitlab-org/security-products/analyzers/find-sec-bugs:10-8-stable

After a short discussion and asking a question Why we chosen to copy the docker pull command instead of only the name?, we've concluded, that this is most probably because Docker Hub also does it. But in case of Docker Hub it's obvious what will happened:

By looking on this part of Docker Hub's image page user clearly see, that it's a Docker Pull Command that will be copied. Additionally, a docker pull image/name is clearly printed bellow.

While with our registry:

There is no information that would suggest it's docker pull ... command that will be copied. What is more problematic, the tooltip - that is showed when the copy button is hovered - prints only the name of the image what may convince the user that his assumption is right!

We should either change the copied content (which I would vote for!, since I almost never used this button to simply call the docker pull ... command, but many times used it to copy the long name of the image to put it later in some configuration file... and then I needed to go back to the beginning of the line and remove the docker pull string) or describe it clearly that it's Docker Pull command, that will be copied - not the name of the image.