Docs/mm/damon/design: update the layout based on the layers

DAMON design document is describing only the operations set layer and
monitoring part of the core logic.  Update the layout based on the DAMON's
layers, so that more parts of DAMON including DAMOS core logic and DAMON
modules can easily be added.

Link: https://lkml.kernel.org/r/20230525214314.5204-5-sj@kernel.orgSigned-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Documentation/mm/damon/design.rst

@@ -19,8 +19,8 @@ DAMON subsystem is configured with three layers including
   interfaces for the user space, on top of the core layer.
 
 
-Configurable Layers
-===================
+Configurable Operations Set
+---------------------------
 
 DAMON provides data access monitoring functionality while making the accuracy
 and the overhead controllable.  The fundamental access monitorings require
@@ -42,8 +42,8 @@ Also, if some architectures or devices support special optimized access check
 primitives, those will be easily configurable.
 
 
-Reference Implementations of Address Space Specific Monitoring Operations
-=========================================================================
+Operations Set Layer
+====================
 
 The monitoring operations are defined in two parts:
 
@@ -105,8 +105,12 @@ conflict with the reclaim logic using ``PG_idle`` and ``PG_young`` page flags,
 as Idle page tracking does.
 
 
-Address Space Independent Core Mechanisms
-=========================================
+Core Logics
+===========
+
+
+Monitoring
+----------
 
 Below four sections describe each of the DAMON core mechanisms and the five
 monitoring attributes, ``sampling interval``, ``aggregation interval``,
@@ -115,7 +119,7 @@ regions``.
 
 
 Access Frequency Monitoring
----------------------------
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 The output of DAMON says what pages are how frequently accessed for a given
 duration.  The resolution of the access frequency is controlled by setting
@@ -142,7 +146,7 @@ size of the target workload grows.
 
 
 Region Based Sampling
----------------------
+~~~~~~~~~~~~~~~~~~~~~
 
 To avoid the unbounded increase of the overhead, DAMON groups adjacent pages
 that assumed to have the same access frequencies into a region.  As long as the
@@ -159,7 +163,7 @@ assumption is not guaranteed.
 
 
 Adaptive Regions Adjustment
----------------------------
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 Even somehow the initial monitoring target regions are well constructed to
 fulfill the assumption (pages in same region have similar access frequencies),
@@ -178,7 +182,7 @@ keeping the bounds users set for their trade-off.
 
 
 Dynamic Target Space Updates Handling
--------------------------------------
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 The monitoring target address range could dynamically changed.  For example,
 virtual memory could be dynamically mapped and unmapped.  Physical memory could