- added minimal relaxng examples

example_catalog/my_relaxng_test.rng

+<?xml version="1.0" encoding="UTF-8"?>
+<grammar 
+    xmlns="http://relaxng.org/ns/structure/1.0"
+    xmlns:a="http://relaxng.org/ns/compatibility/annotations/1.0"
+    datatypeLibrary="http://www.w3.org/2001/XMLSchema-datatypes"
+    ns="my_relaxng_test">
+    <start>
+        <element name="addressBook" >
+            <oneOrMore>
+                <element name="card">
+                    <element name="name">
+                        <text/>
+                    </element>
+                    <element name="email">
+                        <text/>
+                    </element>
+                </element>
+            </oneOrMore>
+        </element>        
+    </start>
+</grammar>

example_catalog/schema_catalog.xml

@@ -36,5 +36,6 @@
    <entry schematype="schema" namespace="http://www.w3.org/2005/Atom" schemauri="https://schemas.opengis.net/kml/2.3/atom-author-link.xsd"/>
    <entry schematype="schema" namespace="http://www.opengis.net/gml/3.2" schemauri="https://schemas.opengis.net/gml/3.2.1/gml.xsd"/>
    <entry schematype="relaxng" namespace="http://docbook.org/ns/docbook" schemauri="https://docbook.org/xml/5.1/rng/docbook.rng"/>
+   <entry schematype="relaxng" namespace="my_relaxng_test" schemauri="my_relaxng_test.rng" />
 
 </slubschemacatalog>

resources/test/invalid/my_relaxng_test.invalid.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<addressBook xmlns="my_relaxng_test"/>

resources/test/valid/my_relaxng_test.valid.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<addressBook xmlns="my_relaxng_test">
+    <card>
+        <name>John Smith</name>
+        <email>js@example.com</email>
+    </card>
+</addressBook>