[css-speech] Update the viewport meta tag

Author: xfq

css-speech-1/Overview.html

@@ -7,7 +7,7 @@
 
   <link href="https://www.w3.org/TR/2018/NOTE-css3-speech-20180206/"
    rel=canonical>
-  <meta content="width=device-width" name=viewport>
+  <meta content="width=device-width, initial-scale=1, shrink-to-fit=no" name="viewport">
   <link href="http://purl.org/dc/terms/" rel=schema.dcterms>
   <link href="https://www.w3.org/Consortium/Legal/ipr-notice#Copyright"
    rel=dcterms.rights>