Document `rectangle-mark-mode'.

* doc/emacs/mark.texi (Mark):
* doc/emacs/killing.texi (Rectangles): Document `rectangle-mark-mode'.

* etc/NEWS: Related edit.

doc/emacs/ChangeLog

@@ -1,3 +1,8 @@
+2014-03-02  Xue Fuqiao  <xfq@gnu.org>
+
+	* mark.texi (Mark):
+	* killing.texi (Rectangles): Document `rectangle-mark-mode'.
+
 2014-03-01  Glenn Morris  <rgm@gnu.org>
 
 	* search.texi (Query Replace): Mention search-invisible.

doc/emacs/killing.texi

@@ -839,6 +839,13 @@ rectangle shifts right.
 @code{string-rectangle}, but inserts the string on each line,
 shifting the original text to the right.
 
+@findex rectangle-mark-mode
+@cindex rectangular region
+  The command @kbd{C-x SPC} (@code{rectangle-mark-mode}) makes a
+@dfn{rectangular region}.  It is a new feature introduced in GNU Emacs
+24.4, and most commands now are still unaware of it, but kill and yank
+(@pxref{Killing}) do work on the rectangle.
+
 @node CUA Bindings
 @section CUA Bindings
 @findex cua-mode

doc/emacs/mark.texi

@@ -43,6 +43,9 @@ Ordinarily, only the selected window highlights its region; however,
 if the variable @code{highlight-nonselected-windows} is
 non-@code{nil}, each window highlights its own region.
 
+  There is another kind of region: the ``rectangular region''.
+@xref{Rectangles}.
+
 @menu
 * Setting Mark::            Commands to set the mark.
 * Marking Objects::         Commands to put region around textual units.

etc/NEWS

@@ -371,6 +371,7 @@ conventions.  To use it, add it to the `fill-nobreak-predicate' hook.
 +++
 ** Uniquify is enabled by default, with `post-forward-angle-brackets' style.
 
++++
 ** New command `C-x SPC' (`rectangle-mark-mode') makes a rectangular region.
 Most commands are still unaware of it, but kill/yank do work on the rectangle.