Documentation manual: cap intro header width so it flows with the page

src/public/index.html

@@ -8,7 +8,7 @@
   <title>Site Gateway</title>
   <meta name="description" content="Host sites, proxy services, and manage HTTPS from one simple dashboard.">
   <link rel="icon" type="image/png" href="/site-gateway-icon-approved.png">
-  <link rel="stylesheet" href="/styles.css?v=0.16.59">
+  <link rel="stylesheet" href="/styles.css?v=0.16.60">
 </head>
 
 <!-- ================================================================
@@ -451,6 +451,6 @@
   <div id="toast" class="toast" role="status"></div>
   <div id="update-banner" class="update-banner hidden" role="status"><span>A new version of Site Gateway is available.</span><div class="update-banner-actions"><button id="update-banner-refresh" class="button primary">Refresh</button><button id="update-banner-dismiss" class="text-button">Dismiss</button></div></div>
   <!-- App scripts: core (app.js) then extended views/admin (features.js) -->
-  <script src="/app.js?v=0.16.59" defer></script><script src="/features.js?v=0.16.59" defer></script><script src="/select-enhance.js?v=0.16.59" defer></script>
+  <script src="/app.js?v=0.16.60" defer></script><script src="/features.js?v=0.16.60" defer></script><script src="/select-enhance.js?v=0.16.60" defer></script>
 </body>
 </html>

src/public/styles.css

@@ -719,7 +719,7 @@ dialog{max-height:calc(100vh - 28px);overflow:auto}
 .docs{display:block}
 .docs-intro{grid-column:1/-1}
 .docs-layout{width:100%}
-.docs-intro{text-align:left}
+.docs-intro{text-align:left;max-width:900px;margin-left:auto;margin-right:auto}
 .docs-intro>p:not(.eyebrow){margin-left:0;margin-right:0}
 .docs-search-panel{margin-left:0;margin-right:0}