Add documentation for lists of images to the tesseract man page

Signed-off-by: Stefan Weil <sw@weilnetz.de>

doc/tesseract.1.asc

@@ -8,7 +8,7 @@ tesseract - command-line OCR engine
 
 SYNOPSIS
 --------
-*tesseract* 'imagename'|'stdin' 'outputbase'|'stdout' [options...] [configfile...]
+*tesseract* 'imagename'|'listname'|'stdin' 'outputbase'|'stdout' [options...] [configfile...]
 
 DESCRIPTION
 -----------
@@ -24,6 +24,11 @@ IN/OUT ARGUMENTS
 	The name of the input image.  Most image file formats (anything
 	readable by Leptonica) are supported.
 
+'listname'::
+	The name of a text file which lists the names of all input images
+	(one image name per line). The results will be combined in a
+	single file for each output file format (txt, pdf, hocr).
+
 'stdin'::
 	Instruction to read data from standard input