docs: move storage initiator def into storagecommon.rng

Reviewed-by: NJán Tomko <jtomko@redhat.com>
Signed-off-by: NPavel Hrdina <phrdina@redhat.com>

docs/schemas/storagecommon.rng

@@ -39,6 +39,17 @@
     </element>
   </define>
 
+  <define name='initiatorinfo'>
+    <element name='initiator'>
+      <element name='iqn'>
+        <attribute name='name'>
+          <text/>
+        </attribute>
+        <empty/>
+      </element>
+    </element>
+  </define>
+
   <define name="reconnect">
     <element name="reconnect">
       <attribute name="enabled">

docs/schemas/storagepool.rng

@@ -336,17 +336,6 @@
     </element>
   </define>
 
-  <define name='initiatorinfo'>
-    <element name='initiator'>
-      <element name='iqn'>
-        <attribute name='name'>
-          <text/>
-        </attribute>
-        <empty/>
-      </element>
-    </element>
-  </define>
-
   <define name='devextents'>
     <oneOrMore>
       <element name='freeExtent'>