Update web editor documentation

Based on https://gitlab.com/gitlab-com/www-gitlab-com/merge_requests/1045
[ci skip]

doc/workflow/web_editor.md

 # GitLab Web Editor
 
-In GitLab you can create new files and edit existing files using our web editor.
-This is especially useful if you don't have access to a command line or you just want to do a quick fix.
-You can easily access the web editor, depending on the context.
-Let's start from newly created project.
+Sometimes it's easier to make quick changes directly from the GitLab interface
+than to clone the project and use the Git command line tool. In this feature
+highlight we look at how you can create a new file, directory, branch or
+tag from the file browser. All of these actions are available from a single
+dropdown menu.
 
-Click on `Add a file`
-to create the first file and open it in the web editor.
+## Create a file
 
-![web editor 1](web_editor/empty_project.png)
+From a project's files page, click the '+' button to the right of the branch selector.
+Choose **New file** from the dropdown.
 
-Fill in a file name, some content, a commit message, branch name and press the commit button.
-The file will be saved to the repository.
+![New file dropdown menu](img/web_editor_new_file_dropdown.png)
 
-![web editor 2](web_editor/new_file.png)
+---
 
-You can edit any text file in a repository by pressing the edit button, when
-viewing the file.
+Enter a file name in the **File name** box. Then, add file content in the editor
+area. Add a descriptive commit message and choose a branch. The branch field
+will default to the branch you were viewing in the file browser. If you enter
+a new branch name, a checkbox will appear allowing you to start a new merge
+request after you commit the changes.
 
-![web editor 3](web_editor/show_file.png)
+When you are satisfied with your new file, click **Commit Changes** at the bottom.
 
-Editing a file is almost the same as creating a new file,
-with as addition the ability to preview your changes in a separate tab. Also you can save your change to another branch by filling out field `branch`
+![Create file editor](img/web_editor_new_file_editor.png)
 
-![web editor 3](web_editor/edit_file.png)
+## Upload a file
+
+The ability to create a file is great when the content is text. However, this
+doesn't work well for binary data such as images, PDFs or other file types. In
+this case you need to upload a file.
+
+From a project's files page, click the '+' button to the right of the branch
+selector. Choose **Upload file** from the dropdown.
+
+![Upload file dropdown menu](img/web_editor_upload_file_dropdown.png)
+
+---
+
+Once the upload dialog pops up there are two ways to upload your file. Either
+drag and drop a file on the pop up or use the **click to upload** link. A file
+preview will appear once you have selected a file to upload.
+
+Enter a commit message, choose a branch, and click **Upload file** when you are
+ready.
+
+![Upload file dialog](img/web_editor_upload_file_dialog.png)
+
+## Create a directory
+
+To keep files in the repository organized it is often helpful to create a new
+directory.
+
+From a project's files page, click the '+' button to the right of the branch selector.
+Choose **New directory** from the dropdown.
+
+![New directory dropdown](img/web_editor_new_directory_dropdown.png)
+
+---
+
+In the new directory dialog enter a directory name, a commit message and choose
+the target branch. Click **Create directory** to finish.
+
+![New directory dialog](img/web_editor_new_directory_dialog.png)
+
+## Create a new branch
+
+If you want to make changes to several files before creating a new merge
+request, you can create a new branch up front. From a project's files page,
+choose **New branch** from the dropdown.
+
+![New branch dropdown](img/web_editor_new_branch_dropdown.png)
+
+---
+
+Enter a new **Branch name**. Optionally, change the **Create from** field
+to choose which branch, tag or commit SHA this new branch will originate from.
+This field will autocomplete if you start typing an existing branch or tag.
+Click **Create branch** and you will be returned to the file browser on this new
+branch.
+
+![New branch page](img/web_editor_new_branch_page.png)
+
+---
+
+You can now make changes to any files, as needed. When you're ready to merge
+the changes back to master you can use the widget at the top of the screen.
+This widget only appears for a period of time after you create the branch or
+modify files.
+
+![New push widget](img/web_editor_new_push_widget.png)
+
+## Create a new tag
+
+Tags are useful for marking major milestones such as production releases,
+release candidates, and more. You can create a tag from a branch or a commit
+SHA. From a project's files page, choose **New tag** from the dropdown.
+
+![New tag dropdown](img/web_editor_new_tag_dropdown.png)
+
+---
+
+Give the tag a name such as `v1.0.0`. Choose the branch or SHA from which you
+would like to create this new tag. You can optionally add a message and
+release notes. The release notes section supports markdown format and you can
+also upload an attachment. Click **Create tag** and you will be taken to the tag
+list page.
+
+![New tag page](img/web_editor_new_tag_page.png)
+
+## Tips
+
+When creating or uploading a new file, or creating a new directory, you can
+trigger a new merge request rather than committing directly to master. Enter
+a new branch name in the **Target branch** field. You will notice a checkbox
+appear that is labeled **Start a new merge request with these changes**. After
+you commit the changes you will be taken to a new merge request form.
+
+![Start a new merge request with these changes](img/web_editor_start_new_merge_request.png)