First draft on TSDB 2.3 and PG 11 deprecation. (#71)

* First draft on TSDB 2.3 and PG 11 deprecation.

* Update timescaledb/overview/release-notes/index.md

Co-authored-by: Mike Freedman <mike@timescale.com>

* Update timescaledb/overview/release-notes/index.md

* Update timescaledb/overview/release-notes/index.md

* Update timescaledb/overview/release-notes/index.md

* Update timescaledb/overview/release-notes/index.md

* Update timescaledb/overview/release-notes/index.md

* Update timescaledb/overview/release-notes/index.md

* Apply suggestions from code review

Co-authored-by: Erik Nordström <819732+erimatnor@users.noreply.github.com>

Co-authored-by: Ryan Booz <ryan@timescale.com>
Co-authored-by: Mike Freedman <mike@timescale.com>
Co-authored-by: Erik Nordström <819732+erimatnor@users.noreply.github.com>

timescaledb/overview/release-notes/index.md

@@ -15,11 +15,11 @@ we welcome you to visit our Github repo or join our [Slack community](https://sl
 
 For our next release, we plan to add:
 
-- Compression policies on distributed hypertables
-- Partially mutable compressed chunks to support INSERTs into a compressed hypertable.
+- Downgrading between Timescale DB 2.x versions.
+- Elasticity: Move data when expanding or shrinking a multi-node cluster
 - Various bug fixes.
 
-The current GA (Generally Available) version is 2.2.1.
+The current GA (Generally Available) version is 2.3.0.
 
 You can read more about our architecture and design for distributed hypertables
 [here][distributed-hypertables].
@@ -31,9 +31,10 @@ follow these [setup instructions][distributed-hypertables-setup].
 In addition to multi-node, we've also reassessed how some core
 functionality works, and, as a result, made APIs simpler and more consistent,
 while also empowering users with more control and flexibility to customize
-behaviors to suit your needs.  Some of these API updates are **breaking changes**.
+behaviors to suit your needs.  
+Some of these API updates are **breaking changes**.
 
-### What's new in TimescaleDB 2.2.1:
+### What's new in TimescaleDB 2.3.0:
 
 Skip Scan optimization on single node and multinode. This feature offers significant
 improvements in performance of `SELECT` queries with `DISTINCT ON`.
@@ -49,14 +50,14 @@ planning, compression, and policies.
 
 **PostgreSQL 11 deprecation announcement**
 
-Timescale is working hard on our next exciting features. To make that
-possible, we require functionality that is unfortunately absent on
-PostgreSQL 11. For this reason, we will continue supporting PostgreSQL
-11 until mid-June 2021. Sooner to that time, we will announce the
-specific version of TimescaleDB in which PostgreSQL 11 support will be removed.
+Timescale is working hard on our next exciting features. 
+To make that possible, we require functionality 
+that is available in Postgres 12 and above. 
+For this reason, TimescaleDB 2.3 will be the final minor version that supports PostgreSQL 11.  
+TimescaleDB 2.4 will require PostgreSQL 12 or 13.
 
 <highlight type="tip">
-TimescaleDB 2.2.1 is currently GA, and we encourage
+TimescaleDB 2.3 is currently GA, and we encourage
 users to upgrade in testing environments to gain experience and provide feedback on
 new and updated features.
 
@@ -76,6 +77,26 @@ accidentally triggering the load of a previous DB version.**
 
 ## Unreleased
 
+## 2.3.0 (2021-05-25)
+**Features**
+* #3116 Add distributed hypertable compression policies
+* #3162 Use COPY when executing distributed INSERTs
+* #3199 Add GENERATED column support on distributed hypertables
+* #3210 Add trigger support on distributed hypertables
+* #3230 Support for inserts into compressed chunks
+
+**Bugfixes**
+* #3213 Propagate grants to compressed hypertables
+* #3229 Use correct lock mode when updating chunk
+* #3243 Fix assertion failure in decompress_chunk_plan_create
+* #3250 Fix constraint triggers on hypertables
+* #3251 Fix segmentation fault due to incorrect call to chunk_scan_internal
+* #3252 Fix blocking triggers with transition tables
+
+**Thanks**
+* @yyjdelete for reporting a crash with decompress_chunk and identifying the bug in the code
+* @fabriziomello for documenting the prerequisites when compiling against PostgreSQL 13
+
 ## 2.2.1 (2021-05-05)
 
 This maintenance release contains bugfixes since the 2.2.0 release. We