feat(aio): do not display anchor if heading has `no-anchor` class

aio/src/styles/1-layouts/_marketing-layout.scss

@@ -440,6 +440,9 @@ header.bckground-sky.l-relative {
     font-size: 24px;
     font-weight: 300;
     color: white;
+    margin: 0;
+    -webkit-margin-before: 0;
+    -webkit-margin-after: 0;
 
     @media (max-width: 600px) {
       font-size: 18px;

aio/src/styles/2-modules/_heading-anchors.scss

@@ -1,6 +1,10 @@
 .sidenav-content {
   h1, h2, h3, h4, h5, h6 {
 
+    &.no-anchor .header-link {
+      display: none;
+    }
+
     .mat-icon, .material-icons {
       visibility: hidden;
       display: inline-block;