Added v2.0.0 release notes

Author: andvgal

doc/release-notes/energi/release-notes-2.0.0.md

@@ -0,0 +1,44 @@
+Energi Core version 2.0.0 Release Notes
+=======================================
+
+**THIS IS MANDATORY UPGRADE!**
+
+
+Energi Core version 2.0.0 is now available from:
+
+  https://energi.world/downloads
+
+Please report bugs using the issue tracker at github:
+
+  https://github.com/energicryptocurrency/energi/issues
+
+
+How to Upgrade
+--------------
+
+If you are running an older version, shut it down. Wait until it has completely
+shut down (which might take a few minutes for older versions), then depending on
+your operation system:
+
+* for Window run the installer
+* for macos run the installer
+* for Linux unpack to a separate folder and run from there
+
+**NOTE**: version of Energi Core prior to v2.0.0 must not be used with the same data files.
+
+
+v2.0.0 changelog
+----------------
+
+Major changes:
+
+* CHANGED: synced source with Dash v0.12.3.4 release
+    - a LOT of bugfixes and optimizations
+* NEW: Energi Proof-of-Stake mining support
+
+
+Minor changes:
+
+* CHANGED: extended getblock- RPC command output
+* FIXED: to enforce checkpoint hash validation
+* NEW: added minimal chainwork checks