Part of #1139

what's Static Code Analysis, benefits, concept of soundness, etc.

That's about a general introduction that should answer questions like: what can PMD do
for me, why should I use it, what are alternatives, what does PMD not do (e.g. guarantee
bug free software, ...)

Compare PMD to other tools such as Checktyle and FindBugs / SpotBugs focusing on:
Analysis speed, analysis power, scope of rules, maybe a rule equivalency chart where
applicable?