doc/go1.22: mention new #cgo directives

For #56378

Change-Id: I0c9c662c6d765cad6f7bf17fdd648db8d73e429b
Reviewed-on: https://go-review.googlesource.com/c/go/+/522937
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
TryBot-Bypass: Ian Lance Taylor <iant@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>

doc/go1.22.html

@@ -37,6 +37,27 @@ <h3 id="go-command">Go command</h3>
   TODO: complete this section, or delete if not needed
 </p>
 
+<h3 id="cgo">Cgo</h3>
+
+<p><!-- CL 497837 --> The special comment that precedes
+  <code>import</code> <code>"C"</code> may now include two
+  new <code>#cgo</code> directives.
+  <ul>
+    <li>
+      <code>#cgo</code> <code>noescape</code> <code>cFunctionName</code>
+      tells cgo that Go pointers passed to the C function
+      <code>cFunctionName</code> do not escape.
+    </li>
+    <li>
+      <code>#cgo</code> <code>nocallback</code> <code>cFunctionName</code>
+      tells cgo that the C function <code>cFunctionName</code> does
+      not call any Go functions.
+    </li>
+  </ul>
+  See <a href="/cmd/cgo#hdr-Optimizing_calls_of_C_code">the <code>cgo</code>
+  documentation</a> for more details.
+</p>
+
 <h2 id="runtime">Runtime</h2>
 
 <p>