Hard-code electronic resource link text instead of using 856$y

Hard-code electronic resource link text instead of using 856$y

- set the link to be 'Connect to this resource online' instead of
  using whatever is in the 856$y. There are better ways to do this,
  but this works for now. (A future revision could be conditional,
  only mangling the link text for types of records/resources we
  specify.)

Signed-off-by: William Rockwood <wrockwood@tadl.org>