docs: describe the new options -J, --guidestripe, and 'set stripecolor'

doc/nano.1

@@ -101,6 +101,11 @@ executed commands, so they can be easily reused in later sessions.
 .BR \-I ", " \-\-ignorercfiles
 Don't look at the system's \fInanorc\fR nor at the user's \fInanorc\fR.
 .TP
+.BR \-J\ \fInumber ", " \-\-guidestripe= \fInumber
+Draw a vertical stripe at the given column, to help judge the width of the
+text.  (The color of the stripe can be changed with \fBset stripecolor\fR
+in your \fInanorc\fR file.)
+.TP
 .BR \-K ", " \-\-rawsequences
 Interpret escape sequences directly (instead of asking \fBncurses\fR to
 translate them).  If you need this option to get your keyboard to work

doc/nano.texi

@@ -190,6 +190,12 @@ executed commands, so they can be easily reused in later sessions.
 @itemx --ignorercfiles
 Don't look at the system's nanorc file nor at the user's nanorc.
 
+@item -J
+@itemx --guidestripe
+Draw a vertical stripe at the given column, to help judge the width of the
+text.  (The color of the stripe can be changed with @code{set stripecolor}
+in your nanorc file.)
+
 @item -K
 @itemx --rawsequences
 Interpret escape sequences directly (instead of asking @code{ncurses} to
@@ -799,6 +805,10 @@ Display line numbers to the left of the text area.
 @item set locking
 Enable vim-style lock-files for when editing files.
 
+@item set guidestripe @var{number}
+Draw a vertical stripe at the given column, to help judge the width of the
+text.  (The color of the stripe can be changed with @code{set stripecolor}.)
+
 @item set matchbrackets "@var{string}"
 Set the opening and closing brackets that can be found by bracket
 searches.  This may not include blank characters.  The opening set must
@@ -914,6 +924,10 @@ Use the given program to do spell checking and correcting.
 Use this color combination for the status bar.
 @xref{@code{set functioncolor}} for valid color names.
 
+@item set stripecolor @var{fgcolor},@var{bgcolor}
+Use this color combination for the vertical guiding stripe.
+@xref{@code{set functioncolor}} for valid color names.
+
 @item set suspend
 Allow @command{nano} to be suspended.
 

doc/nanorc.5

@@ -145,6 +145,10 @@ Display line numbers to the left of the text area.
 .B set locking
 Enable vim-style lock-files for when editing files.
 .TP
+.B set guidestripe \fInumber
+Draw a vertical stripe at the given column, to help judge the width of the
+text.  (The color of the stripe can be changed with \fBset stripecolor\fR.)
+.TP
 .B set matchbrackets "\fIstring\fP"
 Set the opening and closing brackets that can be found by bracket
 searches.  This may not include blank characters.  The opening set must
@@ -261,6 +265,10 @@ instead of the built-in corrector that calls \fBspell\fR.
 Specify the color combination to use for the status bar.
 See \fBset titlecolor\fR for more details.
 .TP
+.B set stripecolor \fIfgcolor\fR,\fIbgcolor\fR
+Specify the color combination to use for the vertical guiding stripe.
+See \fBset titlecolor\fR for more details.
+.TP
 .B set suspend
 Allow \fBnano\fP to be suspended.
 .TP