fixed tense

Author: Aaron Beckerman

index.html

@@ -38,7 +38,7 @@ <h2>How to Think Like Git</h2>
 
     <p>
     Let's start from scratch.  Assume you are designing a new source 
-    code management system.  How do you do basic version control before
+    code management system.  How did you do basic version control before
     you used a tool for it?  Chances are that you simply copied your 
     project directory to save what it looked like at that point.
     </p>