add code to add anchor elements for headlines

it's now possible to add references to headlines within markdown. Just add
a link to the id of the headline, like:

    Some text, that should [testlink](#headline) to another headline.

    ## Headline

When klicking testlink, browser will jump to the section.
add draft article about build systems

a few sections left and also needs proof reading, but I want
to have a backup in git ;)