Add a description to all pages

I've set up the __includes/headers.inc.php__ file to accept a description if, on each page, you do the following:

```php
$description = "";
```

So now that this function is implemented, we should think of a description for:

- [x] The __home.php__ page (we want the website as a whole to get more traffic and the home page will likely recieve the most).
- [x] The __blog.php__ page (we want the blog to be publicised).
- [x] The __chat.php__ page (we want people to join the community).
- [ ] The __state-of-linux-accessibility__, __what-is-linux.php__ and __webbie-programs.php__ articles (articles are what will bring users).
- [ ] The __mac-os-10.12-video.php__, __ubuntu-17.10-video.php__ and __ubuntu-mate-16.04-video.php__ video pages (I've proven with my youtube channel that videos bring viewers).

Other pages _should_ have descriptions, but are not necessarily as important.