README-builds.html update

[Martijn Verburg]

Hi all,

I'm sitting at FOSDEM and was reminded that we hadn't yet made the effort
to integrate the "How to build OpenJDK" material we've built up over on
adoptopendk.java.net (the incubator site for Adoption Group activities) as
well as tidying up some typos and HTML compatibility warnings in the doc.

Updating a reasonably large document will mean a diff of:

* Whitespace changes
* HTML formatting changes
* Actual content changes

Would people prefer a patch for each type of change? Or are they happy for
what will likely be a reasonably large diff, (which basically means
eyeballing the end result).

Cheers,
Martijn