Some links were still pointing to the (moved) `MaikKlein/ash` repo,
instead of the new shared `ash-rs/ash` repository under this
organisation, GitHub still provides a redirect, but we should aim to
provide the correct link from the get-go. Only the gitter channel
remains as it was impossible to get the room to be renamed. The
`ash-rs/ash` channel exists but there is currently no activity.
