Fixed formatting problem.

README.md

@@ -7,12 +7,16 @@ However, unless you print them out, it's difficult to quickly switch between the
 ### Installing and running the program
 
 To run from source, you need Python 3, and some requirements:
-    pip install -r requirements.txt
-    pip install -r asl-cards/requirements.txt
-    python3 main.py
+```
+pip install -r requirements.txt
+pip install -r asl-cards/requirements.txt
+python3 main.py
+```
 
 If you want to compile it:
-    python3 _freeze.py --output /tmp/aslcards.tar.gz
+```
+python3 _freeze.py --output /tmp/aslcards.tar.gz
+```
 
 ### Analyzing the PDF files
 <img src="doc/analyze-files.png" width="300" align="left" hspace="10">The first time you run the program, it needs to analyze the PDF files, to extract each data card (this only needs to be done once).