add since annotation

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1916583 13f79535-47bb-0310-9956-ffa450edef68

poi-ooxml/src/main/java/org/apache/poi/xwpf/usermodel/Document.java

@@ -77,6 +77,8 @@ public interface Document {
 
     /**
      * SVG graphics (.svg)
+     *
+     * @since POI 5.2.6
      */
     public static final int PICTURE_TYPE_SVG = PictureType.SVG.ooxmlId;
 }