Adds links to and from Discoverability topic in End User Guide

With the moving of the Object Storage API content from a
long-form dev guide to a specification, some topics needed
To be added to the End User Guide.

Change-Id: I7612f3fc5226b627f203a48e669abc9cd1e69a76
Partial-bug: 1392382

doc/user-guide/section_object-api-archive-auto-extract.xml

@@ -6,6 +6,9 @@
     xml:id="archive-auto-extract">
     <?dbhtml stop-chunking?>
     <title>Auto-extract archive files</title>
+    <para>To discover whether your Object Storage system supports this
+        feature, see <xref linkend="discoverability"/>. Alternatively,
+        check with your service provider.</para>
     <para>Use the auto-extract archive feature to upload a tar archive
         file.</para>
     <para>The Object Storage system extracts files from the archive

doc/user-guide/section_object-api-bulk-delete.xml

@@ -6,6 +6,9 @@
     xml:id="bulk-delete">
     <?dbhtml stop-chunking?>
     <title>Bulk delete</title>
+    <para>To discover whether your Object Storage system supports this
+        feature, see <xref linkend="discoverability"/>. Alternatively,
+        check with your service provider.</para>
     <para>With bulk delete, you can delete up to 10,000 objects or
         containers (configurable) in one request.</para>
     <section xml:id="bulk-delete-request">

doc/user-guide/section_object-api-create-large-objects.xml

@@ -5,6 +5,9 @@
     xmlns:xlink="http://www.w3.org/1999/xlink" version="5.0"
     xml:id="large-object-creation">
     <title>Large objects</title>
+    <para>To discover whether your Object Storage system supports this
+        feature, see <xref linkend="discoverability"/>. Alternatively,
+        check with your service provider.</para>
     <para>By default, the content of an object cannot be greater than
         5&nbsp;GB. However, you can use a number of smaller objects to
         construct a large object. The large object is comprised of two

doc/user-guide/section_object-api-create-website.xml

@@ -4,6 +4,9 @@
     xmlns:xlink="http://www.w3.org/1999/xlink" version="5.0"
     xml:id="static-website">
     <title>Create static website</title>
+    <para>To discover whether your Object Storage system supports this
+        feature, see <xref linkend="discoverability"/>. Alternatively,
+        check with your service provider.</para>
     <para>You can use your Object Storage account to create a static
         website. This static website is created with staticweb
         middleware and serves container data with a specified index

doc/user-guide/section_object-api-discoverability.xml

@@ -14,6 +14,12 @@
         <listitem>
             <para><xref linkend="archive-auto-extract"/></para>
         </listitem>
+        <listitem>
+            <para><xref linkend="expire-objects"/></para>
+        </listitem>
+        <listitem>
+            <para><xref linkend="bulk-delete"/></para>
+        </listitem>
         <listitem>
             <para><xref linkend="static-website"/></para>
         </listitem>

doc/user-guide/section_object-api-expire-objects.xml

@@ -5,6 +5,9 @@
     xmlns:xlink="http://www.w3.org/1999/xlink" version="5.0"
     xml:id="expire-objects">
     <title>Schedule objects for deletion</title>
+    <para>To discover whether your Object Storage system supports this
+        feature, see <xref linkend="discoverability"/>. Alternatively,
+        check with your service provider.</para>
     <para>Scheduling an object for deletion is helpful for managing
         objects that you do not want to permanently store, such as log
         files, recurring full backups of a dataset, or documents or