Move web_editor doc to new location

...project/repository/img/web_editor_new_branch_dropdown.png

...ser/project/repository/img/web_editor_new_branch_page.png

...roject/repository/img/web_editor_new_directory_dialog.png

...ject/repository/img/web_editor_new_directory_dropdown.png

...r/project/repository/img/web_editor_new_file_dropdown.png

...ser/project/repository/img/web_editor_new_file_editor.png

...ser/project/repository/img/web_editor_new_push_widget.png

...er/project/repository/img/web_editor_new_tag_dropdown.png

doc/user/project/repository/img/web_editor_new_tag_page.png

...ect/repository/img/web_editor_start_new_merge_request.png

.../project/repository/img/web_editor_upload_file_dialog.png

...roject/repository/img/web_editor_upload_file_dropdown.png

doc/user/project/repository/web_editor.md

doc/workflow/README.md

doc/workflow/web_editor.md