fixing README

tests/diff/README.md

@@ -1,15 +1,17 @@
-`comparediffs` provides a tools for downloading a PDF from two different sources, running pdfparanoia on the files, comparing the outputs byte-for-byte,
-and reporting the results.
+`comparediffs` provides a tool which
+* downloads a PDF from two different sources,
+* runs `pdfparanoia` on both files, and
+* compares the outputs byte-for-byte.
 
 Typical usage is to first establish two `ssh` tunnels to hosts with access to the literature, e.g. via
 `ssh -D 1080 host1` and `ssh -D 1081 host2`. You can then invoke `comparediffs` via
 
     ./comparediffs localhost:1080 localhost:1081 < urls
 
-where urls is a file containing one URL per line (e.g. the example file in this directory).
+where `urls` is a file containing one URL per line (e.g. the example file in this directory).
 
-`comparediffs` creates a subdirectory `pdf/`, in which is stores PDFs. It won't try to download the same PDF twice, so if you fix pdfparanoia you'll
-need to clean out some or all of this subdirectory.
+`comparediffs` creates a subdirectory `pdf/`, in which is stores PDFs. It won't try to download the same PDF twice, so if you make changes to `pdfparanoia` you'll
+want to clean out some or all of this subdirectory.
 
-It's easy to see which PDFs pdfparanoia failed on, as it leaves copies of the scrubbed files with suffixes `.1.cleaned.pdf` and `.2.cleaned.pdf`.
-When pdfparanoia succeeds (or isn't even needed, because the downloaded files were identical), the scrubbed files are removed.
+It's easy to see which PDFs `pdfparanoia` failed on afterwards, as it leaves copies of the scrubbed files with suffixes `.1.cleaned.pdf` and `.2.cleaned.pdf`.
+When `pdfparanoia` succeeds (or isn't even needed, because the downloaded files were identical), the scrubbed files are removed.