Also slightly changed the progress to be more accurate.

The conversion-to-wavelength workflow diagram is getting very large. I
have split out the sections to do with creating the direct-beam and
monitor workspaces to simplify the main workflow diagram. The creation
of the transmission workspace is already split out like this.

Re #20120

- Update the documentation text with the new equation in conversion to Q
for the divergent beam.
- Update the workflow diagrams for the fixed cropping.

Re #20120

Refs #19907

Refs #19907

Refs #19907