Update schedule.html

Adjusted "Before We Start" again!

_includes/dc/schedule.html

@@ -157,7 +157,7 @@ <h3>Day 1</h3>
 	<td>Before starting</td>
 	<td><a href="{{ site.pre_survey }}{{ site.github.project_title }}" target="_blank">Pre-workshop survey</a></td>
       </tr>
-      <tr><td>9:00-9:40am</td> <td> <a href="https://datacarpentry.org/r-socialsci/00-intro.html/">Before We Start</a></td></tr>
+      <tr><td>9:00-9:40am</td> <td> <a href="https://datacarpentry.org/r-socialsci/index.html">Before We Start</a></td></tr>
       <tr><td>9:40-10:20am</td><td><a href="https://datacarpentry.org/r-socialsci/01-intro-to-r.html">Introduction to R Part 1</a></td></tr>
 	    <tr><td>10:20-10:30am</td><td><a>Break</a></td></tr>
 	     	       <tr><td>10:30-11:10am</td><td><a href="https://datacarpentry.org/r-socialsci/01-intro-to-r.html">Introduction to R Part 2</a></td></tr>