Update index.html

Fix broken link

Author: jameswex

docs/demos/index.html

@@ -119,7 +119,7 @@
   <div class="demo-card-cta-button"><a href="/lit/demos/glue.html"></a></div>
 </div>
 <div class="demo-card mdl-cell mdl-cell--6-col mdl-cell--4-col-tablet mdl-cell--4-col-phone">
-  <div class="demo-card-title"><a href="/lithttps://colab.research.google.com/github/PAIR-code/lit/blob/main/lit_nlp/examples/notebooks/LIT_sentiment_classifier.ipynb" target="_blank">Notebook usage</a></div>
+  <div class="demo-card-title"><a href="https://colab.research.google.com/github/PAIR-code/lit/blob/main/lit_nlp/examples/notebooks/LIT_sentiment_classifier.ipynb" target="_blank">Notebook usage</a></div>
   <div class="demo-card-tags"> <span class="demo-tag"> BERT </span>  <span class="demo-tag"> binary classification </span>  <span class="demo-tag"> notebooks </span> 
   </div>
   <div class="demo-card-data-source-title">DATA SOURCES</div>