improved guide for file uploads

docs/dcu-fileupload.md

@@ -3,12 +3,12 @@
 Files can be uploaded via the Editor interface - first choose the library and table, then click "Upload".
 
 
-<img src="/img/dcu-files1.png" height="350" >
+<img src="/img/dcu-files1.png" height="350" style="border:3px solid black" >
 
 The following should be considered when uploading data in this way:
 
  - A header row (with variable names) is required
- - Variable names must be the identical to the target (although this is not case sensitive)
+ - Variable names must match the target
  - Duplicate variable names are not permitted
  - Missing columns are not permitted
  - Additional columns are ignored
@@ -17,3 +17,6 @@ The following should be considered when uploading data in this way:
 
 When loading dates, be aware that the data controller makes use of the `ANYDTDTE` and `ANYDTDTTME` informats.
 This means that uploaded date / datetime values should be unambiguous (eg `01FEB1942` vs `01/02/42`) to avoid confusion - as the latter could be interpreted as `02JAN2042` depending on your locale and options `YEARCUTOFF` settings.
+
+!!! tip
+    To get a copy of a file in the right format for upload, use the [file download](/dc-userguide/#usage) feature in the Viewer tab