docs(stencil): add stencil usage to components (#21261)

core/src/components/content/usage/stencil.md

@@ -0,0 +1,37 @@
+```tsx
+import { Component, h } from '@stencil/core';
+
+@Component({
+  tag: 'content-example',
+  styleUrl: 'content-example.css'
+})
+export class ContentExample {
+  logScrollStart() {
+    console.log('Scroll start');
+  }
+
+  logScrolling(ev) {
+    console.log('Scrolling', ev);
+  }
+
+  logScrollEnd() {
+    console.log('Scroll end');
+  }
+
+  render() {
+    return [
+      <ion-content
+        scrollEvents={true}
+        onIonScrollStart={() => this.logScrollStart()}
+        onIonScroll={(ev) => this.logScrolling(ev)}
+        onIonScrollEnd={() => this.logScrollEnd()}>
+          <h1>Main Content</h1>
+
+          <div slot="fixed">
+            <h1>Fixed Content</h1>
+          </div>
+      </ion-content>
+    ];
+  }
+}
+```