Move "$ref" section below "$id"

Talking about references and dereferencing makes more sense after
we establish base URIs and subschema identfication.

This commit just moves the section, subsequent commits will adjust
the text and titles accordingly.

Author: handrews

jsonschema-core.xml

@@ -527,33 +527,6 @@
             </t>
         </section>
 
-        <section title='Schema References With "$ref"'>
-            <t>
-                The "$ref" keyword is used to reference a schema, and provides the ability to
-                validate recursive structures through self-reference.
-            </t>
-            <t>
-                An object schema with a "$ref" property MUST be interpreted as a "$ref" reference.
-                The value of the "$ref" property MUST be a URI Reference.
-                Resolved against the current URI base, it identifies the URI of a schema to use.
-                All other properties in a "$ref" object MUST be ignored.
-            </t>
-            <t>
-                The URI is not a network locator, only an identifier. A schema need not be
-                downloadable from the address if it is a network-addressable URL, and
-                implementations SHOULD NOT assume they should perform a network operation when they
-                encounter a network-addressable URI.
-            </t>
-            <t>
-                A schema MUST NOT be run into an infinite loop against a schema. For example, if two
-                schemas "#alice" and "#bob" both have an "allOf" property that refers to the other,
-                a naive validator might get stuck in an infinite recursive loop trying to validate
-                the instance.
-                Schemas SHOULD NOT make use of infinite recursive nesting like this; the behavior is
-                undefined.
-            </t>
-        </section>
-
         <section title="Base URI and Dereferencing">
             <section title="Initial Base URI">
                 <t>
@@ -652,6 +625,36 @@
                         <t hangText="#/definitions/C">urn:uuid:ee564b8a-7a87-4125-8c96-e9f123d6766f</t>
                     </list>
                 </t>
+            </section>
+
+            <section title='Schema References With "$ref"'>
+                <t>
+                    The "$ref" keyword is used to reference a schema, and provides the ability to
+                    validate recursive structures through self-reference.
+                </t>
+                <t>
+                    An object schema with a "$ref" property MUST be interpreted as a "$ref" reference.
+                    The value of the "$ref" property MUST be a URI Reference.
+                    Resolved against the current URI base, it identifies the URI of a schema to use.
+                    All other properties in a "$ref" object MUST be ignored.
+                </t>
+                <t>
+                    The URI is not a network locator, only an identifier. A schema need not be
+                    downloadable from the address if it is a network-addressable URL, and
+                    implementations SHOULD NOT assume they should perform a network operation when they
+                    encounter a network-addressable URI.
+                </t>
+                <t>
+                    A schema MUST NOT be run into an infinite loop against a schema. For example, if two
+                    schemas "#alice" and "#bob" both have an "allOf" property that refers to the other,
+                    a naive validator might get stuck in an infinite recursive loop trying to validate
+                    the instance.
+                    Schemas SHOULD NOT make use of infinite recursive nesting like this; the behavior is
+                    undefined.
+                </t>
+            </section>
+
+            <section title="Dereferencing">
                 <section title="Internal References">
                     <t>
                         Schemas can be identified by any URI that has been given to them, including