Add short text introducing PIE

Author: derickr

install/pie.xml

@@ -0,0 +1,37 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- $Revision$ -->
+
+<chapter xml:id="install.pie" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink" annotations="chunk:false">
+ <title>Installation of PIE and third-party extensions</title>
+
+ <sect1 xml:id="install.pie.intro">
+  <title>Introduction to PIE</title>
+  <simpara>
+   &link.pie; is an installer for PHP, that makes it possible to install
+   third-party PHP extensions, that can then be easily installed and updated.
+   It leverages the PHP extension repository part of
+   <link xlink:href="&url.packagist;">Packagist</link> to find the source code
+   to build the extension, or a Windows binary to download, if it exists. If it
+   downloads the source code, it also knows how to build and install it.
+  </simpara>
+  <simpara>
+   After <link xlink:href="&url.pie;?tab=readme-ov-file#what-do-i-need-to-get-started">installing
+   the requirements and PIE itself</link>, you can then install the
+   <link linkend="mongodb.mongodb">MongoDB extension</link> by running the
+   following on the command line.
+  </simpara>
+  <example>
+   <title>Installing the MongoDB extension with PIE</title>
+   <programlisting role="shell">
+<![CDATA[
+pie install mongodb/mongodb-extension
+]]>
+   </programlisting>
+  </example>
+  <simpara>
+   The <link xlink:href="&url.pie;/blob/main/docs/usage.md">"PIE
+   Usage" documentation</link> goes into this in more depth.
+  </simpara>
+
+ </sect1>
+</chapter>