Generic/PHP/Syntax: add XML documentation

Author: rodrigoprimo

src/Standards/Generic/Docs/PHP/SyntaxStandard.xml

@@ -0,0 +1,21 @@
+<documentation title="Syntax">
+    <standard>
+    <![CDATA[
+    The code should use valid PHP syntax.
+    ]]>
+    </standard>
+    <code_comparison>
+        <code title="Valid: No PHP syntax errors.">
+        <![CDATA[
+echo "Hello!";
+$array = [1, 2, 3];
+        ]]>
+        </code>
+        <code title="Invalid: Code contains PHP syntax errors.">
+        <![CDATA[
+echo "Hello!" // Missing semicolon at the end
+$array = [1, 2, 3; // Missing closing bracket
+        ]]>
+        </code>
+    </code_comparison>
+</documentation>