Update of GUI description of CREATE_CSVT option for CSV driver (#61812)

Option CREATE_CSVT also creates a side car PRJ file that stores coordinate system description. I also added this text to GDAL documentation and it is accepted by Even, can be seen in latest version:
https://gdal.org/en/latest/drivers/vector/csv.html#layer-creation-options

Co-authored-by: Nyall Dawson <[email protected]>

Author: phidrho

src/core/qgsvectorfilewriter.cpp

@@ -1179,7 +1179,8 @@ class QgsVectorFileWriterMetadataContainer
 
       layerOptions.insert( QStringLiteral( "CREATE_CSVT" ), new QgsVectorFileWriter::BoolOption(
                              QObject::tr( "Create the associated .csvt file to describe the type of each "
-                                          "column of the layer and its optional width and precision." ),
+                                          "column of the layer and its optional width and precision. "
+                                          "This option also creates a .prj file which stores coordinate system information." ),
                              false  // Default value
                            ) );