Prepare release notes for release v0.4.0 (#199)

Author: llucax

RELEASE_NOTES.md

@@ -6,6 +6,11 @@ This breaking release removes deprecated compatibility modules and symbols, and
 
 ## Upgrading
 
+> [!NOTE]
+> We recommend upgrading first to v0.3.8 and remove all deprecation warnings (and implicit conversions of enum values to protobuf messages) before upgrading to v0.4.0.
+>
+> By doing so you'll be guided by the deprecation warnings and when you are done, upgrading to v0.4.0 should imply not extra work.
+
 * Passing enum values directly to build protobuf messages is not longer supported, you need to call the conversion functions `xxx_(from|to)_proto_v1alpha8()` explicitly.
 * Replace `frequenz.client.common.metric.Metric` with `frequenz.client.common.metrics.Metric`.
 * Replace `frequenz.client.common.microgrid.components` imports with `frequenz.client.common.microgrid.electrical_components` imports.
@@ -14,11 +19,3 @@ This breaking release removes deprecated compatibility modules and symbols, and
 * Replace `PaginationInfo.from_proto()`, `PaginationInfo.to_proto()`, and `PaginationInfo.to_proto_v1alpha8()` with `frequenz.client.common.pagination.proto.v1alpha8` conversion functions.
 * Replace `frequenz.client.common.pagination.Info` with `frequenz.client.common.pagination.PaginationInfo`.
 * Use API-provided `v1alpha8` pagination protobuf messages directly instead of `frequenz.client.common.pagination.Params`.
-
-## New Features
-
-<!-- Here goes the main new features and examples or instructions on how to use them -->
-
-## Bug Fixes
-
-<!-- Here goes notable bug fixes that are worth a special mention or explanation -->