Improve inclusion of external files

Create a link of `files' directory in order to have the inclusion of external
files works on local and on the website (after publication).
Complete the article about suspending Linux

The article about problem with suspending Linux was incomplete (probably
a forget in saving the file).
[article] Using sed to add new lines

This article explains how to add a new lines after a found pattern.
Complete metadata of all articles

Add a few metadata to each article likes tags, language, slug and category.