Improve wiki re #6896

Signed-off-by: Karl Palmen <karl.palmen@stfc.ac.uk>

Code/Mantid/Framework/DataHandling/src/ModifyDetectorDotDatFile.cpp

@@ -1,14 +1,30 @@
 /*WIKI* 
 
-Modifies an ISIS detector dot data file, so that the detector positions are as in the given workspace. This algorithm can be used to transfer a calibration done via the [[ApplyCalibration]] algorithm to an ISIS detector dot dat file by selecting a workspace that has been modified by ApplyCalibration.
-
-
+Modifies an ISIS detector dot data file, so that the detector positions are as in the given workspace. 
+This algorithm can be used to transfer a calibration done via the [[ApplyCalibration]] algorithm to an ISIS detector dot dat file 
+by selecting a workspace that has been modified by ApplyCalibration.
+
+A typical ISIS dot data file has a format like this:
+
+ DETECTOR.DAT generated by CREATE_DETECTOR_FILE
+  286729      14
+  det no.  offset    l2     code     theta        phi         w_x         w_y         w_z         f_x       ...       
+      11   0.000  -3.25800     1   180.00000     0.00000     0.00000     0.00000     0.00000     0.00000    ... 
+      21   0.000  -1.50400     1   180.00000     0.00000     0.00000     0.00000     0.00000     0.00000    ...
+    ....
+ 1110001   5.300   2.88936     3    52.28653  -140.67224     0.02540     0.02540     0.00283     0.02750   ... 
+ 1110002   5.300   2.88794     3    52.26477  -140.72720     0.02540     0.02540     0.00283     0.02750   ...
+    ....
+
+Each row corresponds to a detector whose type is indicated in the <code>code</code> column.
+The algorithm will only modify values in colums <code>l2</code>, <code>theta</code> and <code>phi</code> and 
+only if the value in the <code>code</code> column is 3, which indicates a PSD gas tube.
+For more details about the detector dot data file see [[LoadDetectorInfo#File_format]].
 
 *WIKI*/
 #include "MantidAPI/FileProperty.h"
 #include "MantidAPI/MatrixWorkspace.h"
 #include "MantidDataHandling/ModifyDetectorDotDatFile.h"
-// #include "MantidDataHandling/LoadDetectorInfo.h"
 #include "MantidGeometry/Instrument.h"
 #include "MantidGeometry/Instrument/RectangularDetector.h"
 #include "MantidKernel/System.h"