add pdf definition

glossary.tex

@@ -351,6 +351,12 @@
   prefix={a\space},
   ]{piy}{PiY}{Print it Yourself}
 
+\newacronym[
+  description={means that the file is for printing, not for reading on a screen},
+  prefix={a\space},
+  nonumberlist,
+  ]{pdf}{pdf}{Printable Document Format}
+
 \newglossaryentry{weight}{
   name={Weight Rating},
   text={Weight},