Update README for plaintext handling

README.md

@@ -11,14 +11,17 @@ A minority of printers support only PCL and/or their own proprietary formats, th
 
 ## Format support
 
-For PDFs or plaintext, your printer needs to support one of the following formats:
+For PDFs, your printer needs to support one of the following formats:
  * PDF
  * Postscript
  * PWG-raster
  * URF-raster
 
 For Postscript, your printer needs to support Postscript natively. (SeaPrint just sends it as-is)
 
+For Plaintext, SeaPrint can render it to PDF internally and then the requirements follow those of PDF.
+You can also send Plaintext to supporting printers and leave the rendering up to the printer (SeaPrint will strip leading and trailing Form Feed characters and ensure CR-NL newlines, but not do any reflow or similar). Since rendering will differ between printers, this has lowest priority for automatic format selection.
+
 For printing "Office" files, like .doc(x) and odt, you need to install
  `calligraconverter` (from the `calligra` package in Sailfish OS 4.2 onwards).
  Then the printer support follows that of PDF.