Encourage the use of the stable packages per disro norms. The devel
packages can be used but they trigger full git clones in many AUR
helpers and are generally a pain if you don't specifically want them for
something. Mention the devel package but update the URLs to point to
the one that uses the normal packaging system.

The `mr` utilily is now called myrepos upstream and they have a new
website address. Update the links in the readme, reflect the new name
of the project where appropriate, and fix the copy surrounding its
introdiction. The actual command is still `mr`.

Table syntax in GFM?  Oh, yes: 
<https://github.com/adam-p/markdown-here/wiki/Markdown-Cheatsheet#tables>

Git supports the push -u flag since a while now,
and it's nice to show the user that afterwards
one can push without arguments

* Add 30 second overview
* Make GitHub parse intra-document MarkDown links
  Sadly, the MarkDown specs are missing this feature

Thanks to Flavius Aspra for the Arch Linux howto