docs: move notes inside the body of the document

Make all documents start with a heading.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

docs/devel/multi-process.rst

-This is the design document for multi-process QEMU. It does not
-necessarily reflect the status of the current implementation, which
-may lack features or be considerably different from what is described
-in this document. This document is still useful as a description of
-the goals and general direction of this feature.
-
-Please refer to the following wiki for latest details:
-https://wiki.qemu.org/Features/MultiProcessQEMU
-
 Multi-process QEMU
 ===================
 
+.. note::
+
+  This is the design document for multi-process QEMU. It does not
+  necessarily reflect the status of the current implementation, which
+  may lack features or be considerably different from what is described
+  in this document. This document is still useful as a description of
+  the goals and general direction of this feature.
+
+  Please refer to the following wiki for latest details:
+  https://wiki.qemu.org/Features/MultiProcessQEMU
+
 QEMU is often used as the hypervisor for virtual machines running in the
 Oracle cloud. Since one of the advantages of cloud computing is the
 ability to run many VMs from different tenants in the same cloud