put page nos. inside tokens

pages/common/pdftotext.md

@@ -16,4 +16,4 @@
 
 - Convert pages 2, 3 and 4 of input.pdf to plain text and save them as output.txt:
 
-`pdftotext -f 2 -l 4 {{input.pdf}} {{output.txt}}`
+`pdftotext -f {{2}} -l {{4}} {{input.pdf}} {{output.txt}}`