> - the main docs are version specific, while this kind of page
> should be version independent

They could still be included in the main docs with a clear link at the top that says "For the most-recently updated schedule see d.p.o/3/eol.html.".  Each version should still be correct -- it will just lack the eol dates for the newest releases.
The Unicode Consortium and the W3C do something similar (see e.g. http://www.unicode.org/reports/tr29/tr29-23.html and http://www.w3.org/TR/2014/WD-html5-20140617/).

Another option is to create a new repo where to put version-independent docs (e.g. the whatsnew, maybe even Misc/NEWS).  It shouldn't be difficult to then include these pages in the main docs.