CHANGELOG in preparation for v20

Change-Id: Ib3bd8ef89367138ba9aa0afee032b255b25aed75
diff --git a/CHANGELOG b/CHANGELOG
index e63367e..d59a811 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,24 +1,41 @@
 Unreleased:
   Tracing service and probes:
+    *
+  Trace Processor:
+    *
+  UI:
+    *
+  SDK:
+    *
+
+
+v20.0 - 2021-10-03:
+  Tracing service and probes:
     * Removed DCHECK that would cause crashes when a debug build of the service
       is used with a producer built with -DNDEBUG.
     * Changed the service-side field-level filtering configuration protobuf
       field number, because the feature had a bug. This is effectively
       equivalent to deprecating the feature and reintroducing it under a
       different name.
+    * Added support for boot tracing on Android. Early kernel tracing (prior to
+      the point when /data is mounted) is not yet supported. For instructions
+      see /docs/case-studies/android-boot-tracing.md .
   Trace Processor:
     * Added reqiurement of separating queries by semi-colon (;) followed by
       new-line when specifying a query file with -q to trace processor shell.
     * Added "ancestor_slice_by_stack" and "descendant_slice_by_stack" table
       functions to walk up and down the slice stacks.
     * Overhauled windowed sorting to be based on packet ordering and
-      lifecycle events inside the trace instead of time-based ordering. 
-    * Deprecated |SortingMode::kForceFlushPeriodWindowedSort| due to
-      windowed sorting chagnes. Embedders should switch to
-      |SortingMode::kDefaultHeuristics|; this option will be removed
-      in v21.
+      lifecycle events inside the trace instead of time-based ordering.
+    * Removed |SortingMode::kForceFlushPeriodWindowedSort| due to changes to the
+      sorting algorithm, which is now based on Flush events rather than time.
+      Embedders should switch to |SortingMode::kDefaultHeuristics|. Other
+      SortingMode enum values are no-ops and will be removed in future versions.
   UI:
-    *
+    * Added initial flamegraph support for traced_perf callstack samples.
+    * Added initial Pivot table for aggregation of userspace slices. The feature
+      is disabled by default for and requires manual enabling via
+      https://ui.perfetto.dev/#!/flags .
   SDK:
     * Changed DCHECK and DLOGs to be always disabled in SDK builds, regardless
       of NDEBUG.