- added hint to schema catalog file

README.md

@@ -30,7 +30,16 @@ Schemas
 .......
 
 * the plugin uses local schema files to validate schema/schematron/relaxng related XML files.
-* the schema directory is specified via plugin settings
+* the schema catalog file has following structure: 
+```
+<?xml version="1.0" encoding="UTF-8"?>
+<slubschemacatalog>
+   <entry schematype="schema" namespace="http://www.loc.gov/mods/v3" schemaurl="http://www.loc.gov/standards/mods/v3/mods-3-8.xsd" />
+   <entry schematype="schema" namespace="http://www.lido-schema.org" schemaurl="http://www.lido-schema.org/schema/v1.1/lido-v1.1.xsd" />
+   <entry schematype="schema" namespace="http://slubarchiv.slub-dresden.de/rights1" schemaurl="https://slubarchiv.slub-dresden.de/fileadmin/groups/slubsite/slubarchiv/standards/rights/rights1.xsd" />
+   <entry schematype="schema" namespace="http://www.loc.gov/standards/alto/ns-v2#" schemaurl="http://www.loc.gov/standards/alto/alto-v2.0.xsd" />
+</slubschemacatalog>
+```
 
 
 For a (german) introduction how to use it, check https://www.data2type.de/xml-xslt-xslfo/docbook/xml-kataloge