added images and fixed starting a shell doc

doc/gitlab_basics/basicsimages/image_file.png

doc/gitlab_basics/basicsimages/issue_title.png

doc/gitlab_basics/basicsimages/issues.png

doc/gitlab_basics/basicsimages/key.png

doc/gitlab_basics/basicsimages/merge_requests.png

doc/gitlab_basics/basicsimages/new_issue.png

doc/gitlab_basics/basicsimages/new_merge_request.png

doc/gitlab_basics/basicsimages/new_project.png

doc/gitlab_basics/basicsimages/newbranch.png

doc/gitlab_basics/basicsimages/paste_sshkey.png

doc/gitlab_basics/basicsimages/profile_settings.png

doc/gitlab_basics/basicsimages/project_info.png

doc/gitlab_basics/basicsimages/public_file_link.png

doc/gitlab_basics/basicsimages/select_branch.png

doc/gitlab_basics/basicsimages/select_project.png

doc/gitlab_basics/basicsimages/settings.png

doc/gitlab_basics/basicsimages/shh_keys.png

doc/gitlab_basics/basicsimages/submit_new_issue.png

doc/gitlab_basics/basicsimages/title_description_mr.png

doc/gitlab_basics/basicsimages/white_space.png