chore: rename ctx to cx

docs/posts/04-hooks.md

@@ -1,17 +1,16 @@
-
 ```rust
-fn Example(ctx: &mut Context<()>) -> VNode {
-    let service = use_combubulator(ctx);
+fn Example(cx: &mut Context<()>) -> VNode {
+    let service = use_combubulator(cx);
     let Status { name, pending, count } = service.info();
-    html! { 
-        <div> 
+    html! {
+        <div>
             <p> "Hello, {name}!" </p>
             <p> "Status: {pending}!" </p>
             <p> "Count {count}!" </p>
-            <button onclick=|_| service.update()> 
+            <button onclick=|_| service.update()>
                 "Refresh services"
             </button>
-        </div> 
+        </div>
     }
 }
 ```