Fix grammar issue on index
<ul>
<li>Basic programming concepts</li>
<ul>
- <li>Knowing how control-flow <i>(if / while / for)</i> work under-the-hood.</li>
+ <li>Knowing how control-flow <i>(if / while / for)</i> works under-the-hood.</li>
<li>General feel for how to design a basic program <i>(Intuitive feel for identifying logic in potentially obfuscated files)</i></li>
</ul>
<li>Java's class file design</li>
