Remove .html extension from links

chrome/common/extensions/docs/templates/articles/manifest/externally_connectable.html

 <h1>externally_connectable</h1>
 
 <p>
-The <code>externally_connectable</code> manifest property declares which extensions, apps, and web pages can connect to your {{platform}} via <a href="../runtime.html#method-connect">runtime.connect</a> and <a href="../runtime.html#method-sendMessage">runtime.sendMessage</a>.
+The <code>externally_connectable</code> manifest property declares which extensions, apps, and web pages can connect to your {{platform}} via <a href="../runtime#method-connect">runtime.connect</a> and <a href="../runtime#method-sendMessage">runtime.sendMessage</a>.
 </p>
 
 <p>
-For a tutorial on message passing see <a href="../messaging.html#external">cross-extension and app messaging</a> and <a href="../messaging.html#external-webpage">sending messages from web pages</a>.
+For a tutorial on message passing see <a href="../messaging#external">cross-extension and app messaging</a> and <a href="../messaging#external-webpage">sending messages from web pages</a>.
 </p>
 
 <h2 id="without-externally-connectable">Connecting without externally_connectable</h2>
 
 <p>
 If <code>externally_connectable</code> is not declared in your {{platform}}'s manifest, all extensions and apps can connect, but no webpages can connect. As a consequence, when updating your manifest to use <code>externally_connectable</code>, if <code>"ids": ["*"]</code> is not specified then other extensions and apps will lose the ability to connect to your {{platform}}. This may be an unintended consequence, so keep it in mind.
 </p>
 
 <h2 id="manifest">Sample manifest.json</h2>
 <pre data-filename="manifest.json">
@@ skipping 24 matching lines @@
     "accepts_tls_channel_id": false
   },
   ...
 }
 </pre>
 
 <h2 id="reference">Reference</h2>
 <p class="api_reference">
 {{+partials.type type:apis.extensionsManifestTypes.byName.ExternallyConnectable/}}
 </p>