doc: exiv2.org moved to exiv2.dyndns.org
Upstream changed doc links here:
https://github.com/Exiv2/exiv2/commit/b48dfc2a2a6fa95539b049d23075358b5b3eecc7
Upstream changed doc links here:
https://github.com/Exiv2/exiv2/commit/b48dfc2a2a6fa95539b049d23075358b5b3eecc7