Add PHPDoc config

.gitignore

@@ -1,3 +1,5 @@
 .idea
+.phpdoc
+_site
 vendor
 *-tests.txt

phpdoc.dist.xml

@@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="UTF-8" ?>
+<phpdocumentor
+        configVersion="3"
+        title="PDODocument"
+        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+        xmlns="https://www.phpdoc.org"
+        xsi:noNamespaceSchemaLocation="https://raw.githubusercontent.com/phpDocumentor/phpDocumentor/master/data/xsd/phpdoc.xsd">
+    <paths>
+        <output>_site/api</output>
+        <cache>.phpdoc/cache</cache>
+    </paths>
+    <version number="2.1.0">
+        <api>
+            <source dsn=".">
+                <path>src</path>
+            </source>
+            <visibility>public</visibility>
+            <default-package-name>PDODocument</default-package-name>
+        </api>
+    </version>
+    <setting name="template.color" value="blue" />
+</phpdocumentor>