Edit Page link for keyboards should edit the keyboard repo, not help repo

[mcdurdin]

e.g. On this page: https://help.keyman.com/keyboard/sil_ipa/1.8.2/sil_ipa, the Edit Page link currently goes to https://github.com/keymanapp/help.keyman.com/edit/master/keyboard/sil_ipa/1.8.2/sil_ipa.php but should go to https://github.com/keymanapp/keyboards/edit/master/release/sil/sil_ipa/source/help/sil_ipa.php.

There would be lookup required to find the appropriate path, so it may be better to make the Edit link go to an redirect page which does that lookup, rather than try to do the lookup on every page load.