Use modelica:// URIs

[dietmarw]

Some of the Image linkes use relative links. You should better use modelica://

See for example:
https://github.com/raulrpearson/PVSystems/blob/master/PVSystems/package.mo#L19
Which should become:

  <p><img src=\"modelica://PVSystems/Resources/Images/TypicalSystem.png\"