Clarify a bit the manpage

doc/mat2.1

@@ -74,9 +74,9 @@ 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. 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,
+processed files. For example, textual based pdf file converted into image based
+one means that it'll be no longer possible to select text in them. If you're
+experiencing this, you might want to give the lightweight cleaning mode a try,
 but keep in mind by doing so, some metadata \fBwon't be cleaned\fR.