docs: remove mention of the quotestr for when regex support is lacking

Since version 2.8.0, nano will use (wnen needed) the regex routines
from gnulib, so mentioning the quotestr for when regex support is
lacking, has been obsolete and pointless for more than a year.

Also, remove some superfluous backslashes, use a non-breaking space
in the texinfo document, and order the regex consistently.

doc/nano.1

@@ -124,9 +124,7 @@ and place it at that position again upon reopening such a file.
 .TP
 .BR "\-Q ""\fIcharacters\fB""" ", " "\-\-quotestr=""" \fIcharacters """
 Set the quoting string for justifying.  The default is
-\fB"^([\ \\t]*[#:>\\|}])+"\fP if extended regular expression support is
-available, or \fB">\ "\fP otherwise.  Note that \fB\\t\fP stands for a
-Tab.
+\fB"^([\ \\t]*[#:>|}])+"\fP.  Note that \fB\\t\fP stands for an actual Tab.
 .TP
 .BR \-R ", " \-\-restricted
 Restricted mode: don't read or write to any file not specified on the

doc/nano.texi

@@ -221,8 +221,7 @@ and place it at that position again upon reopening such a file.
 @item -Q "@var{characters}"
 @itemx --quotestr="@var{characters}"
 Set the quoting string for justifying.  The default value is
-@t{"^([ \t]*[|>:@}#])+"} if extended regular expression support
-is available, and @t{"> "} otherwise.
+@t{"^([@w{ }\t]*[#:>|@}])+"}.
 Note that @code{\t} stands for a literal Tab character.
 
 @item -R
@@ -848,10 +847,8 @@ Obsolete option.  Recognized but ignored.
 
 @item set quotestr "@var{string}"
 The email-quote string, used to justify email-quoted paragraphs.  This
-is an extended regular expression if your system supports them,
-otherwise a literal string.  The default value is
-@t{"^([ \\t]*[#:>\\|@}])+"} if you have extended regular expression
-support, and @t{"> "} otherwise.
+is an extended regular expression.  The default value is
+@t{"^([@w{ }\t]*[#:>|@}])+"}.
 Note that @code{\t} stands for a literal Tab character.
 
 @item set rebinddelete

doc/nanorc.5

@@ -203,10 +203,8 @@ Obsolete option.  Recognized but ignored.
 .TP
 .B set quotestr "\fIstring\fP"
 The email-quote string, used to justify email-quoted paragraphs.  This
-is an extended regular expression if your system supports them,
-otherwise a literal string.  The default value is
-"\fB^([\ \\t]*[#:>\\|}])+\fP" if you have extended regular expression
-support, and "\fB>\ \fP" otherwise.  Note that '\\t' stands for a literal
+is an extended regular expression.  The default value is
+"\fB^([\ \\t]*[#:>|}])+\fP".  Note that \fB\\t\fR stands for an actual
 Tab character.
 .TP
 .B set rebinddelete

doc/sample.nanorc.in

@@ -125,12 +125,8 @@
 # set quickblank
 
 ## The email-quote string, used to justify email-quoted paragraphs.
-## This is an extended regular expression if your system supports them,
-## otherwise a literal string.
-## If you have extended regular expression support, the default is:
-# set quotestr "^([ 	]*[#:>\|}])+"
-## Otherwise:
-# set quotestr "> "
+## This is an extended regular expression.  The default is:
+# set quotestr "^([ 	]*[#:>|}])+"
 
 ## Fix Backspace/Delete confusion problem.
 # set rebinddelete