fix: getting started example missing style

https://code.getmdl.io/1.2.1/material.indigo-pink.min.css has gone

Author: joriszwart

examples/getting-started-codelab/complete-code/index.html

@@ -9,7 +9,7 @@
 
     <link
       rel="stylesheet"
-      href="https://code.getmdl.io/1.2.1/material.indigo-pink.min.css" />
+      href="https://unpkg.com/material-design-lite@1.3.0/dist/material.indigo-pink.min.css" />
     <link rel="stylesheet" href="styles/index.css" />
   </head>
 

examples/getting-started-codelab/starter-code/index.html

@@ -9,7 +9,7 @@
 
     <link
       rel="stylesheet"
-      href="https://code.getmdl.io/1.2.1/material.indigo-pink.min.css" />
+      href="https://unpkg.com/material-design-lite@1.3.0/dist/material.indigo-pink.min.css" />
     <link rel="stylesheet" href="styles/index.css" />
   </head>