release notes for v0.5.2 (#240)

* added release notes for v0.5.2

* removed compatilibity statement from release notes

* Update doc/release-notes/tapyrus/release-notes-0.5.2.md

Co-authored-by: shigeyuki azuchi <azuchi@chaintope.com>

* Update doc/release-notes/tapyrus/release-notes-0.5.2.md

Co-authored-by: shigeyuki azuchi <azuchi@chaintope.com>

Co-authored-by: shigeyuki azuchi <azuchi@chaintope.com>

doc/release-notes/tapyrus/release-notes-0.5.2.md

@@ -0,0 +1,42 @@
+Tapyrus version 0.5.2 is now available for download at:
+  https://github.com/chaintope/tapyrus-core/releases/tag/v0.5.2
+
+Please report bugs using the issue tracker at github:
+  https://github.com/chaintope/tapyrus-core/issues
+
+Project source code is hosted at github; you can get
+source-only tarballs/zipballs directly from there:
+  https://github.com/chaintope/tapyrus-core/tarball/v0.5.2
+
+
+How to Upgrade
+==============
+
+It is recommended to upgrade all older nodes, v0.5.0 and 0.5.1 to the latest release as it contains critical bug fixes. If you are running a node on tapyrus testnet follow the instruction in [getting_started](doc/tapyrus/getting_started.md#how-to-start-a-node-on-tapyrus-testnet) to sart a new Tapyrus v0.5.2 node.
+
+If you are running a private tapyrus network using versions v0.3.0, v0.4.0 or v0.4.1, shut it down. Wait until it has completely shut down. Follow the instruction in [getting_started](doc/tapyrus/getting_started.md#how-to-start-a-new-tapyrus-network) to sart a new Tapyrus v0.5.2 network. Please note that tapyrus-signer network should also be upgraded following [tapyrus signer network setup](https://github.com/chaintope/tapyrus-signer/blob/master/doc/setup.md#how-to-set-up-new-tapyrus-signer-network)
+
+
+Downgrading warning
+-------------------
+
+Tapyrus blockchain created by older versions(v0.3.0, v0.4.0 and v0.4.1) is not compatible with v0.5.2 and vice-versa.
+
+Compatibility
+==============
+
+Tapyrus v0.5.2 is supported on three platforms, Linux, MacOS and Windows(WSL) in two CPU architectures namely x86_x64 and arm64(aarch64)
+
+0.5.2 change log
+------------------
+
+*Federation Management*
+
+Tapyrus-core version v0.5.2 contains critical bug fixes to make Federation Management reliable:
+ 1. Adding a new node to the tapyrus-core network after an aggregate public key update(using xField in the block header) is now supported.
+ 2. A node restarted after aggregate pubkey update can now use the block tree db key to persist and retrieve the list of aggpubkeys instead of using `-reindex`.
+ 3. A new command line argument `-reloadxfield` is added to create the block tree db entry in older nodes while upgrading.
+
+*Token issue fee*
+
+Fee required to issue new tokens/colored coins is made to match the network fee rate. It was _one Tapyrus_ more than the network fee rate until now.