Merge pull request #329 from AndrejMitrovic/Fixup123

[minor] Changelog typo's
fix download link for dmd2 windows exe
Merge branch 'master' of github.com:D-Programming-Language/d-programming-language.org
use numbered lists in changelog
S3 download links except for OSX
Correction of request to change `immutable` fields to `immutable`.

Not sure this is a correct correction.
Merge pull request #330 from denis-sh/patch-3

Correction of request to change `immutable` fields to `immutable`.
Add docs for documented unittests.