Updated markdown and gitlab documentation

Help/Git-and-Gitlab.md

-### Info about Markdown
-
-Markdown is a markup language that is used in Gitlab for documentation text files. Markdown files have a .md extension and can be edited locally or online. However, for best results, we recommend editing files locally and then uploading them. There are good guides to the syntax [here](https://confluence.atlassian.com/stash/using-stash/markdown-syntax-guide) and [here](https://en.wikipedia.org/wiki/Markdown). 
-
-### Editing
-You can also edit markdown files locally, using a text editing application (such as TextEdit) or a word processing program (such as Word). However, be aware that some word processing programs may affect line breaks and formatting, which may change how information is displayed.
-
-You can edit markdown files from the Gitlab web site. From the Gitlab home page, click a project on the right
-side. On the project home page, click "Files" in the left navigation bar. Click a .md file. Click the "Edit"
-button on the right side. Update the text and when finished, enter a commit message below, and click the
-"Commit Changes" button.
-
-#### Markdown, local complete reference
-http://gitlab.iath.virginia.edu/help/markdown/markdown.md
-
-#### Markdown, same info, somewhat different format
-https://help.github.com/articles/markdown-basics/
-
-#### Github extensions to standard markdown:
-https://help.github.com/articles/github-flavored-markdown/
-
-#### Standard markdown notes:
-https://github.com/adam-p/markdown-here/wiki/Markdown-Cheatsheet
-
 ### Working locally and version control
 
 The Git technology was created to track revisions to many files. Gitlab provides a web site with some ability

Help/Markdown.md

+### Info about Markdown
+
+Markdown is a markup language that is used in Gitlab for documentation text files. Markdown files have a .md extension and can be edited locally or online. However, for best results, we recommend editing files locally and then uploading them. There are good guides to the syntax [here](https://confluence.atlassian.com/stash/using-stash/markdown-syntax-guide) and [here](https://en.wikipedia.org/wiki/Markdown).
+
+### Editing
+You can edit markdown files locally, rather than on the website.  One full-featured cross-platform Markdown editor is [Atom](http://atom.io).  After opening a file, pressing `Ctrl-Shift-M` for Win/Linux and `Cmd-Shift-M` for Mac will open a real-time preview of the markdown file.
+
+![Atom Screenshot](../images/atom-screenshot.png "Screenshot of Atom editing Interface")
+
+You can also edit markdown files using a text editing application (such as TextEdit or Notepad). However, be aware that some word processing programs may affect line breaks and formatting, which may change how information is displayed.  
+
+You can edit markdown files from the Gitlab web site. From the Gitlab home page, click a project on the right
+side. On the project home page, click "Files" in the left navigation bar. Click a .md file. Click the "Edit"
+button on the right side. Update the text and when finished, enter a commit message below, and click the
+"Commit Changes" button.
+
+### Resources
+
+* [Gitlab markdown reference (local)](http://gitlab.iath.virginia.edu/help/markdown/markdown.md)
+* [Github markdown reference](https://help.github.com/articles/markdown-basics/)
+* [Github extensions to standard markdown](https://help.github.com/articles/github-flavored-markdown/)
+* [Alternate markdown cheatsheet](https://github.com/adam-p/markdown-here/wiki/Markdown-Cheatsheet)
+* [Official Markdown documentation](http://daringfireball.net/projects/markdown/)