(bug 44160) Fix invalid link of `others` during installation

On the `Environmental Checks` page during MW installation, the link to
`others` in Credits was invalid because it points to a local special
page and the wiki is not even installed.

Changed the link to
`http://www.mediawiki.org/wiki/Special:Version/Credits` which is
always available during installation.

Change-Id: I3967e14303f9db7def39c97982f06e6086bb69b8
Merge "(bug 44160) Fix invalid link of `others` during installation"