Merge pull request #26 from linkedin/fixes

Add requirements.txt, local build documentation, misc fixes

courses/CONTRIBUTING.md

@@ -3,3 +3,12 @@ We realise that the initial content we created is just a starting point and our
 As a contributor, you represent that the content you submit is not plagiarised. By submitting the content, you (and, if applicable, your employer) are licensing the submitted content to LinkedIn and the open source community subject to the BSD 2-Clause license.
 
 We suggest to open an issue first and seek advice for your changes before submitting a pull request.
+
+### Building and testing locally
+Run the following commands to build and view the site locally before opening a PR.
+
+```
+pip install -r requirements.txt
+mkdocs build
+mkdocs serve
+```

courses/linux_basics/intro.md

@@ -1,6 +1,7 @@
-# Introduction
+# Linux Basics
 
-## Prerequisites
+## Introduction
+### Prerequisites
 
 - Comfortable using any operating systems like Windows, Linux or Mac
 - Fundamental knowledge of operating systems

courses/stylesheets/custom.css

@@ -0,0 +1 @@
+div.md-content img { border: 4px solid #ddd; padding: 12px; }