Heading in Web IDE's empty state should be updated
Summary
Following the discussion in https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/26556#note_157794317 to Make and review changes in the browser with the Web IDE
instead of Welcome to the GitLab IDE
This text update is for any time we load WebIDE with no files open.
Relevant logs and/or screenshots
Edited by Pedro Moreira da Silva