docs/core-api: rename memory-hotplug-notifier to memory-hotplug

to allow additions of new documentation about memory hotplug under the same
roof.

Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/core-api/index.rst

@@ -32,7 +32,7 @@ Core utilities
    gfp_mask-from-fs-io
    timekeeping
    boot-time-mm
-   memory-hotplug-notifier
+   memory-hotplug
 
 
 Interfaces for kernel debugging

Documentation/core-api/memory-hotplug.rst

@@ -1,6 +1,9 @@
-.. _memory_hotplug_notifier:
+.. _memory_hotplug:
+
+==============
+Memory hotplug
+==============
 
-=============================
 Memory hotplug event notifier
 =============================