Add better descriptions to the form text

[kmader]

The form text needs to be updated to include

• what do INVALID DATA, CASE and PATIENT even meen

[kmader]

The tags indicate - INVALID DATA: the patient and case seem reasonable but the images should be redownloaded since the slice counts don't match or a series is incorrect or missing, INVALID CASE: the patient has NSCLC but this is the wrong case / accession number and a different one should be found for staging, INVALID PATIENT: the patient does not have NSCLC and should be completely removed from this project and not examined again. RECURRENCE is an additional tag to INVALID CASE (check both) since we might want to look at recurrence cases later.