Update tag-based workflow diagrams to include tximport

Now that tximport helps us process tag-based data, we should update the workflow?

Start by locating the existing tag-based workflow diagrams and reviewing how tximport is currently used in the training modules. Update the relevant diagrams to show tximport in the tag-based data-processing workflow, then verify that the rendered diagrams accurately reflect the workflow.

Written by the indexing model from the issue text.