GitLab basics overhaul: create a group

From @rdickenson's video teardown (https://www.youtube.com/watch?v=7OwGuAfbFPY) of https://docs.gitlab.com/ee/user/group/index.html#create-a-new-group, improve the documentation using the following notes:

• Link text on landing page doesn't match the title of the section linked to.
• Screenshots break into the numbered list. Could group them under the numbered list.
• References to colour of button aren't helpful to some audiences.
• References to path don't match the screenshot.
• Process doesn't complete with clicking the button to finish the process.

Suggestions:

• Rename section to Create a group.
• Generally edit the text.
• Remove references to colour.
• Add "Click the Create group button" step.

Note: Some of the text in this section has already been updated in a separate MR: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/27609.

@rdickenson anything else?

CC @gl-docsteam

added docsimprovement documentation labels

changed the description

added to epic &1179

added [deprecated] Accepting merge requests label

removed [deprecated] Accepting merge requests label

added devopsfulfillment devopsgrowth labels

added devopsfulfillment devopsgrowth labels

added devopssystems groupdistribution labels and removed devopsfulfillment devopsgrowth labels

added devopscreate groupgitter labels and removed devopssystems groupdistribution labels

added groupgitaly label and removed groupgitter label

added 1 deleted label and removed groupgitaly label

removed devopscreate + 1 deleted label

Setting label(s) Technical Writing based on docsimprovement.

changed the description

added Technical Writing label