Docs update

ChoiceColumns.php

@@ -103,9 +103,11 @@ protected function pageTop() {
                 $(choices).each(function(i, e) {
                     let r, c;
                     if (horizontal) {
+                        // horizontal alignment -> across then down, r then c
                         r = Math.trunc(i / nCols);
                         c = i % nCols;
                     } else {
+                        // vertical alignment -> down then across, c then r
                         c = Math.trunc(i / nRows);
                         r = i % nRows;
                     }

README.md

@@ -14,6 +14,7 @@ Notes:
 * The tag is ignored for radio and checkbox fields that are part of a matrix.
 * Enhanced radio buttons and checkboxes are supported.
 * Specify an integer in the range 1-99 for the number of columns. Any other value will cause the tag to be ignored and the field display default behaviour.
+* Choices hidden through `@HIDECHOICE` or `@SHOWCHOICE` are removed from the column/row grid (i.e. there will not be blank placeholder spaces for hidden choices).
 * Piping into the action tag *is* supported, but only on page load. It is not dynamic within a page (i.e. is similar to other tags like `@HIDECHOICE` and `@IF`).
 
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