Add documentation for changes to Show Paren mode.

* lisp/paren.el (show-paren-highlight-openparen): Enhance doc string.

* doc/emacs/programs.texi (Matching): Add descriptions of some pertinent user
options, including the new show-paren-when-point-inside-paren and
show-paren-when-point-in-periphery.

* etc/NEWS (.. Specialized Modes ...): Add an entry for Show Paren mode.
Move an entry on pcase to the Lisp Changes section.

1 files changed, 7 insertions, 0 deletions

diff --git a/etc/NEWS b/etc/NEWS
index a09db1642c7..4c5ce3e4207 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -623,6 +623,13 @@ invalid certificates are marked in red.
 *** text/html messages that contain inline image parts will be
 transformed into multipart/related messages before sending.
 
++++
+** In Show Paren Mode, a parenthesis can be highlighted when point
+stands inside it, and certain parens can be highlighted when point is
+at BOL or EOL, or in whitespace there.  To enable these, customize,
+respectively, show-paren-when-point-inside-paren or
+show-paren-when-point-in-periphery.
+
 ** pcase
 *** New UPatterns `quote', `app', `cl-struct', and `eieio'.
 *** New UPatterns can be defined with `pcase-defmacro'.