Better explain effect of smearing in concatenated data

[butlerpd]

Following up on issue #353 where user was confused that when they applied the dQ from file they got spikes in their data which did not "look correct." The documentation was updated to indicate that resolution is worst next to beamstop so if you intercalate data from two setting you will mix points with bad resolution next to some with good. Also suggested this could be avoided by a simultaneous fit. While true this fails to emphasize to point out that SasView is demonstrating the fact that the intensity at a given Q should be different for different resolutions. This is important because most users do not understand this. More importantly, because they don't, they tend to scale data from different settings so that they "look" like they match in the overlap region - which is often wrong. Thus there is in fact value in noting that this fit actually provides valuable information: if the "spikiness" of the model is worse than the data, it is clear evidence the user incorrectly scaled their data which could be a nice sanity check.