Fix a typo and grammatical error in prefetch-src (#288)

index.src.html

@@ -2442,7 +2442,7 @@ <h5 algorithm id="media-src-post-request">
 
   <h4 id="directive-prefetch-src">`prefetch-src`</h4>
 
-  The <dfn export>prefetch-src</dfn> directive restrictes the URLs from which resources may be
+  The <dfn export>prefetch-src</dfn> directive restricts the URLs from which resources may be
   prefetched or prerendered. The syntax for the directive's name and value is described by the
   following ABNF:
 
@@ -2458,7 +2458,7 @@ <h4 id="directive-prefetch-src">`prefetch-src`</h4>
       Content-Security-Policy: <a>prefetch-src</a> https://example.com/
     </pre>
 
-    Fetches for the following code will return network errors, as the URLs provided does not match
+    Fetches for the following code will return network errors, as the URLs provided do not match
     `prefetch-src`'s <a>source list</a>:
 
     <pre highlight="html">