chore: add CHANGELOG.md file

Author: janezicmatej

CHANGELOG.md

@@ -0,0 +1,41 @@
+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
+and this project adheres to
+[Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+# \[[v0.2.0](<>) (Upcoming)\]
+
+### Changed
+
+- **BREAKING CHANGE:** `RPC_URL` environment variable was renamed to
+  `RPC_BASE_URL` and now only expects base rpc url (without `/ext/bc/C/rpc` at
+  the end)
+
+### Added
+
+- fast updates addresses are periodically checked for sufficient balance
+- periodically check for unclaimed rewards
+- check for registration and preregistration
+- check if transactions are made against correct contracts
+- check if transactions are sent too early or too late (before they were just
+  reported as missing)
+- check uptime for validator nodes
+- validate fast updates participation
+- sample minimal conditions for ftso, fast updates, fdc and validator nodes
+- add a global try except and report when there are issues with the rpc
+
+### Fixed
+
+- fixed bug where the observer loop would crash at the beggining of next
+
+# \[[v0.1.0](https://github.com/flare-foundation/fsp-observer/tree/v0.1.0)\] - 2025-06-16
+
+### Added
+
+- fdc round validation
+- ftso round validation
+- entity addresses are periodically checked for sufficient balance
+- notifications plugins for discord, slack, telegram, generic http post