fix typo preset -> present

Reported-By: Brandon Fosdick <bfoz@bfoz.net>

index.html

@@ -9,7 +9,7 @@ layout: reference
     reference for learning and remembering the most important and
     commonly used Git commands.  The commands are organized into
     sections of the type of operation you may be trying to do, and
-    will preset the common options and commands needed to accomplish
+    will present the common options and commands needed to accomplish
     these common tasks.
     </p>
     <p>