Update installation instructions for MacOS (#4525)

* Add note about pkgconf and openssl being required
* Mention shivammathur/extensions tap containing the latest version

Author: alcaeus

reference/mongodb/configure.xml

@@ -100,6 +100,27 @@ extension=mongodb.so
    using the <link linkend="install.pecl">pecl</link> command provided by the
    Homebrew PHP installation.
   </para>
+  <para>
+   Alternatively, the
+   <link xlink:href="https://github.com/shivammathur/homebrew-extensions">shivammathur/extensions tap</link>
+   provides formulae for individual PHP extensions. For example, to install the
+   extension for PHP 8.4, run:
+   <programlisting role="shell">
+<![CDATA[
+$ brew install shivammathur/extensions/[email protected]
+]]>
+   </programlisting>
+   Please note that only the latest extension version is available in brew.
+  </para>
+  <note>
+   <title>Install required dependencies</title>
+   <para>
+    To ensure that SSL support can be configured correctly, make sure that the
+    <literal>openssl</literal> and <literal>pkgconf</literal> formulae are
+    installed. If either of these packages are missing, the extension will be
+    compiled with Secure Transport, which can lead to compatibility issues.
+   </para>
+  </note>
  </section>
 
  <section xml:id="mongodb.installation.windows">