Add an example of possible quality loss in the manpage

doc/mat2.1

@@ -74,9 +74,10 @@ be cleaned or not.
 .PP
 Moreover, mat2 goes to great lengths to make sure that as much metadata as
 possible are removed. This might sometimes result in a loss of quality of the
-processed files. If you're experiencing this, you might want to give the
-lightweigtht cleaning mode a try, but keep in mind by doing so, some metadata
-\fBwon't be cleaned\fR.
+processed files. For example, textual based pdf file converted into image
+based means you'll be no longer able to copy text from pdf them. If you're
+experiencing this, you might want to give the lightweigtht cleaning mode a try,
+but keep in mind by doing so, some metadata \fBwon't be cleaned\fR.
 
 
 .SH BUGS

[georg]

@jvoisin Should this read be no longer able to copy text from pdf then.?

[georg]

Typo: lightweight