Update tracking docs.

Author: mrmrs

docs/typography/tracking/index.html

@@ -85,7 +85,7 @@ <h4 class="f1 ttu tracked bold mt0">Title Example</h4>
   <h3 class="f5 fw4 sans-serif pt4 caps black-100">Mega Tracked</h3>
   <h4 class="f1 ttu tracked-mega bold mt0">Title Example</h4>
   <h3 class="f5 fw4 sans-serif pt4 caps black-100">Tightly Tracked</h3>
-  <h4 class="f-headline ttu tracked-tight bold mt0">Title Example</h4>
+  <h4 class="f-headline tracked-tight bold mt0">title example</h4>
   <div class="mt5 cf">
     <div class="dib mr4">
       <h1 class="f4 ttu tracked fw6">Previous</h1>

src/templates/docs/tracking/index.html

@@ -58,7 +58,7 @@ <h4 class="f1 ttu tracked bold mt0">Title Example</h4>
   <h3 class="f5 fw4 sans-serif pt4 caps black-100">Mega Tracked</h3>
   <h4 class="f1 ttu tracked-mega bold mt0">Title Example</h4>
   <h3 class="f5 fw4 sans-serif pt4 caps black-100">Tightly Tracked</h3>
-  <h4 class="f-headline ttu tracked-tight bold mt0">Title Example</h4>
+  <h4 class="f-headline tracked-tight bold mt0">title example</h4>
   <div class="mt5 cf">
     <div class="dib mr4">
       <h1 class="f4 ttu tracked fw6">Previous</h1>