docs: mention the ability to read from stdin

Also, remove the special "+line,column" argument from among the options,
since it isn't an option -- put it in a separate paragraph instead.

doc/nano.1

@@ -34,6 +34,13 @@ top of copying Pico's look and feel, \fBnano\fP also implements some
 missing (or disabled by default) features in Pico, such as "search and
 replace" and "go to line and column number".
 
+When opening a file, the cursor can be put on a specific line by adding
+the line number with a plus sign (\fB+\fR) before the filename, and even
+in a specific column by adding it with a comma.
+
+If the first file specified is a dash (\fB\-\fR), \fBnano\fR will read
+data from standard input.
+
 .SH EDITING
 Entering text and moving around in a file is straightforward: typing the
 letters and using the normal cursor movement keys.  Commands are entered
@@ -61,11 +68,6 @@ The default key bindings can be changed via the .nanorc file -- see
 
 .SH OPTIONS
 .TP
-.B +\fIline\fP,\fIcolumn\fP
-Places the cursor on line number \fIline\fP and at column number \fIcolumn\fP
-(at least one of which must be specified) on startup, instead of the
-default line 1, column 1.
-.TP
 .BR \-A ", " \-\-smarthome
 Make the Home key smarter.  When Home is pressed anywhere but at the
 very beginning of non-whitespace characters on a line, the cursor will

doc/nano.texi

@@ -101,13 +101,18 @@ But it is also possible to specify one or more options, and to edit
 several files in a row.  Additionally, the cursor can be put on a
 specific line of a file by adding the line number
 with a plus sign before the filename, and even in a specific column by
-adding it with a comma.  So the complete command synopsis is:
+adding it with a comma.
+
+Also, if the first file specified is a dash, @code{nano} will read
+data from standard input.
+
+So a more complete command synopsis is:
 
 @quotation
 @code{nano [OPTION]@dots{} [[+LINE[,COLUMN]|+,COLUMN] FILE]@dots{}}
 @end quotation
 
-But normallly you would set your preferred options in your
+But normally you would set your preferred options in your
 @file{.nanorc} file.  And when the @code{positionlog} option is set
 (making @code{nano} remember the cursor position when you close a file),
 you will rarely need to specify a line number.
@@ -120,10 +125,6 @@ you will rarely need to specify a line number.
 
 @table @option
 
-@item +@var{line},@var{column}
-Start at line number @var{line} and column number @var{column} (at least one of
-which must be specified) instead of the default of line 1, column 1.
-
 @item -A
 @itemx --smarthome
 Make the Home key smarter.  When Home is pressed anywhere but at the