replace diff_match_patch_python installation steps with pip-installing it now that I've put it in pip

Author: JoshData

README.md

@@ -13,16 +13,8 @@ The script is written in Python 3, and it relies on the `pdftotext` program.
 Installation
 ------------
 
-	sudo apt-get install libxml2-dev libxslt1-dev poppler-utils # on Ubuntu, at least
-	sudo pip3 install pillow lxml
-
-	# get my Python extension module for the Google Diff Match Patch library
-	# so we can compute differences in text very quickly
-	git clone --recursive https://github.com/JoshData/diff_match_patch-python
-	cd diff_match_patch-python
-	sudo apt-get install python3-dev
-	python3 setup.py build
-	sudo python3 setup.py install
+	sudo apt-get install python3-lxml poppler-utils # on Ubuntu, at least
+	sudo pip3 install pillow lxml diff_match_patch_python
 
 Running
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