fix repolinter issues: add CHANGELOG

Add CHANGELOG with release information from GitHub,
https://github.com/hyperledger-labs/perun-node/releases.

Signed-off-by: Chris Hoeppler <christian.hoeppler@de.bosch.com>

CHANGELOG.md

@@ -0,0 +1,111 @@
+# Changelog
+
+## [0.6.0](https://github.com/hyperledger-labs/perun-node/releases/tag/v0.6.0) – 2021-07-08
+
+perun-node v0.6.0 is a regular development release.
+
+Newly added:
+
+  1. Implemented a new app with text based UI (TUI) for trying out
+     perun-node.
+  2. Validate contracts during node initialization.
+  3. Added an example for directly using the payment API by importing
+     `perun-node` module. See [app/payment/payment_test.go](app/payment/payment_test.go).
+  4. Updated the payment API to allow use of ERC20 token as currency. 
+     * A channel can be opened with balances in more than one
+       currency.
+     * Multiple payments involving different currencies can be made in a
+       single API call.
+     * Asset contracts for ERC20 tokens can be specified in node config
+       file or registered via API.
+
+Improvements:
+
+  1. Improved error handling. The errors returned by API provide a rich
+     context and necessary data in structured format for easy error
+     handling.
+  2. Use structured logging. Request and response (success or error) are
+     logged in a structured format for each API call.
+  3. Use weak (scrypt) encryption parameters for ethereum keystore
+     wallets by default. This makes the `open session` action in tests and
+     in CLI/TUI apps to be much faster.
+
+For detailed information on changes covered in this release, see
+milestone [12](https://github.com/hyperledger-labs/perun-node/milestone/12).
+
+## [0.5.0](https://github.com/hyperledger-labs/perun-node/releases/tag/v0.5.0) – 2020-12-18
+
+perun-node v0.5.0 is a regular development release.
+
+Newly added:
+
+  1. Support for payment requests. User can send (decrease own balance) or
+     request (increase own balance) money when sending state channel updates.
+  2. Support for running integration tests in Circle CI continuous integration
+     pipeline.
+
+Improvements:
+
+  1. Added unit tests in session package. Previously only integration tests were
+     implemented in this package.
+  2. Channel logger is now derived from session logger. So each log entry for
+     the channel also includes the fields registered on session logger.
+     (currently it is only session-id).
+  3. Re-organized definition of configuration parameters used in tests for
+     easier maintenance and update.
+
+For detailed information on changes covered in the this release, see
+milestone [11](https://github.com/hyperledger-labs/perun-node/milestone/11).
+
+## [0.4.0](https://github.com/hyperledger-labs/perun-node/releases/tag/v0.4.0) – 2020-10-19
+
+perun-node v0.4.0 is the first regular development release after complete re-implementation done in v0.3.0.
+
+Newly added:
+
+  1. `perunnode` executable binary for running an instance of perun node.
+  2. `perunnodecli` interactive application as reference client implementation
+     for connecting to perun node.
+  3. Implemented option to close a session.
+  4. Support for persistence. Close a session with open channels, restore it
+     later and transact on the restored channels.
+
+Improvements:
+
+  1. Updated go-perun dependency to include the following changes:
+     * Channel nonce is created from randomness contributed from both
+       participants of the channel.
+     * Use of transactor interface abstraction for initializing contract
+       backend.
+  2. Updated payment channel API to use consistent data formats.
+  3. Combined channel close subscription and channel update subscription into
+     one.
+
+For detailed information on changes covered in the this release, see
+milestone [10](https://github.com/hyperledger-labs/perun-node/milestone/10).
+
+## [0.3.0](https://github.com/hyperledger-labs/perun-node/releases/tag/v0.3.0) – 2020-08-26
+
+perun-node v0.3.0 is a complete re-implementation of the previous version
+(project name changed from dst-go to perun-node). This version uses the
+[go-perun](https://github.com/hyperledger-labs/go-perun) SDK that implements a
+state channel client based on perun protocol and builds other functionalities on
+top of that.
+
+The following features are included:
+
+  1. Ethereum backend for blockchain.
+  2. Key management using ethereum keystore.
+  3. YAML file based contacts provider.
+  4. Session (as an abstraction) for enabling multiple users use the same node
+     with dedicated contacts provider and key manager.
+  5. Two party payment channel API for the user over gRPC protocol.
+
+For detailed information on changes covered in this release, see milestones
+[3](https://github.com/hyperledger-labs/perun-node/milestone/3),
+[4](https://github.com/hyperledger-labs/perun-node/milestone/4),
+[5](https://github.com/hyperledger-labs/perun-node/milestone/5),
+[6](https://github.com/hyperledger-labs/perun-node/milestone/6),
+[7](https://github.com/hyperledger-labs/perun-node/milestone/7),
+[8](https://github.com/hyperledger-labs/perun-node/milestone/8), and
+[9](https://github.com/hyperledger-labs/perun-node/milestone/9).