Emphasis on “continue” and “ongoing”, both of which appear in the document:

There is nothing within this document that limits the inquiry to the Ukraine matter.

The resolution spells out that Republicans can suggest subpoenas or witnesses but must submit justifications in writing and they can be vetoed by Democrats. This is obviously to prevent Republicans from flooding the proceedings with bullshit and conspiracy theories. It’s an easy prediction to make, but expect Republicans to flood the process with bullshit subpoenas and witnesses which will get rejected, and continue to complain about process.