updated release notes of v0.2.0

Signed-off-by: Nir Rozenbaum <[email protected]>

release-notes/v0.2.0.md

@@ -1,4 +1,77 @@
-v0.2.0 Release Notes
-====================
+Hub-of-Hubs v0.2.0 Release Notes
+================================
 
-Version `v0.2.0` of `Hub-of-Hubs`.
+* Compatible with ACM v2.3. 
+* Go Version 1.16
+
+----
+In this document we refer to the central management hub as `Hub-of-Hubs` or `HoH`, and to the connected hubs as 
+`Hubs`(also referred to as `Leaf Hubs` or `LHs`).
+
+The following features are included in this release:
+
+### New design of status-transport-bridge component
+* Scales to 1M Managed Clusters and status from a total of 100M Policies across all 1M Managed Clusters, while having 
+potential to scale by at least another order of magnitude.
+* Introduced conflation mechanism which guarantees the component performs well under load and overload.
+* Database related optimizations and tuning. Working with bulk updates instead of updating tables row by row, tables indices optimizations.
+* Optimized data structures for data that is kept in memory. 
+
+### Spec Path Optimizations
+* Introduced a self-adjusting mechanism for efficient frequency of spec updates from the Hub-of-Hubs to the Hubs.
+* Added usage of k8s worker pool in the Hubs for parallelism of deploying/deleting resources that are received 
+from the Hub-of-Hubs.
+
+### RBAC
+RBAC implementation for Hub-of-Hubs resources that are stored in the HoH database.
+
+### Hub-of-Hubs UX
+Implemented a prototype to allow users to view in UI both Policies and Managed Clusters stored in the HoH database.  
+Partially implemented a REST API to fetch the resources from the database. This feature is integrated with HoH RBAC.
+
+### Support for Kafka as transport layer 
+[Apache Kafka](https://kafka.apache.org/) is an event bus technology that uses stream processing and aims to provide a 
+unified, high-throughput, low-latency platform for handling real-time data streams.  
+With the introduction of Kafka as a transport option, we've introduced delta bundles and the data model has been changed 
+to use a hybrid mode of full state and delta state bundles.  
+Hybrid mode updates is used in this version to report compliance status of Policies.
+
+### Message Compression
+Message compression is supported in both directions. current version supports `gzip` compression type.  
+it's possible to define a `no-op` compressor to disable compression.  
+
+### Statistics
+Added basic statistics in HoH for monitoring/analysis.
+
+### Enable all components to run in cluster
+Current version supports running all Hub-of-Hubs components in cluster, including `Kafka` and `PostgreSQL`.
+
+### Database High Availability
+Support for running `PostgreSQL` database in HA mode.  
+Performed performance tests to ensure there is no performance degradation.
+
+### Status Aggregation
+Hubs can be configured via Hub-of-Hubs to report only aggregated status of their resources.  
+This version supports only two levels of aggregation - full/minimal.
+
+### Local Policies
+Local Policies and Placement Rules that are created in the Hubs are reported to the Hub-of-Hubs and stored in the database.  
+In this version, it's possible to view local Policies and Placement Rules only in the database.
+
+### Heartbeats
+Heartbeats of the Hubs are sent to the Hub-of-Hubs to ensure liveness of the Hubs.
+
+### Enable different periodic sync interval for different bundles
+Introduced the option to define different sync intervals for different bundles in the Hubs.  
+This feature may be used to distinguish between high and low priority updates.
+
+### Bundle Version
+Introduced the use of incarnation as part of the bundle version. every time the HoH Agent is restarted in the Hub 
+(may happen due to a failure), incarnation is increased. This may be used to determine whether a given bundle is newer 
+than a different bundle.
+
+### Deployment Automation Scripts
+Automation scripts to deploy Hub-of-Hubs and Hub-of-Hubs Agent on the Hubs.
+
+### Bugs Fix
+Fixed issues that were found in all repos.