Translate markdown files into asciidoc files

We are going to convert all of our documentation from markdown to
asciidoc format, in order to take advantage of the additional features
and semantic elements that asciidoc offers such as automatic section
numbering, admonitions and automatic table of contents (TOC) generation.

Converting README.md by hand is going to be extremely tedious.

As such, as a step towards the full conversion of our documentation to
asciidoc, let's enlist the help of pandoc[1] to translate our
documentation.

The translation is done with pandoc 2.2.1 via this shell script:

    for x in $(find -name '*.md'); do
        pandoc -f markdown_github-hard_line_breaks --wrap=preserve --atx-headers -o "${x%*.md}.adoc" "$x"
    done

While the majority of the translation is done faithfully, there are
still some errors here and there in the translated files. We will be
fixing them in subsequent commits.

[1] http://pandoc.org/