Add a rule intro

Author: afs

shacl12-inf-rules/index.html

@@ -465,7 +465,20 @@
 
     <section id="introduction">
       <h2>Introduction</h2>
-      <p>Inference Rules</p>
+
+      <p>
+        This document introduces the concept of Inference Rules for SHACL 1.2, a mechanism for
+        deriving new RDF triples from existing data using declarative rules defined in shapes
+        graphs. This extends SHACL’s capabilities beyond validation, enabling reasoning and data
+        enrichment.
+      </p>
+
+      <p>
+        This document complements other SHACL 1.2 specifications, such as SHACL Core, by defining
+        the syntax and semantics of rule-based inference. While SHACL Core focuses on constraint
+        validation, the Inference Rules specification provides a standardized way to express and
+        evaluate rules that generate new data.
+      </p>
 
       <section id="terminolgy">
         <h3>Terminology</h3>