Tweak home page titles, typos

Author: jordanmccullough

index.html

@@ -104,10 +104,10 @@ <h2>Downloads to reference anytime</h2>
 
 <section class="grey">
   <div class="container center">
-    <h2>Contributions for the greater good</h2>
+    <h2>Community contributions</h2>
 
     <p>
-      Would you like to update or clarifiy content in the slides or workboks?<br>
+      Would you like to update or clarifiy content in the slides or workbooks?<br>
       Just fork the repository, make your changes, and submit a Pull Request.
     </p>