docs: add CHANGELOG.md (#220)

This PR introduces a changelog to the repository, ensuring clear
documentation of changes, improvements, and updates across releases. By
maintaining a changelog, we aim to:

- **Improve Transparency**: Provide developers and users with a clear
record of new features, fixes, and breaking changes.
- **Enhance Collaboration**: Enable contributors to stay informed about
the evolution of the codebase.
- **Facilitate Communication**: Easily track progress and updates.

## Implementation

- A `CHANGELOG.md` file has been added at the root of the repository.
- The changelog format adheres to [Keep a
Changelog](https://keepachangelog.com/en/1.0.0/) guidelines, ensuring
consistency and clarity.
- Initial entries include the most recent version and its functionality.

## Proposed Workflow

- All PRs introducing new features, fixes, or breaking changes should
include a changelog update.
- Use semantic versioning for tracking changes, with clear tags for
**added**, **changed**, **deprecated**, **fixed**, and **removed**
items.

## Future Steps

- Update the contribution guidelines to include a section on maintaining
the changelog.

CHANGELOG.md

@@ -0,0 +1,41 @@
+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+Changelog is present since v0.1.2
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+Each version will have a separate `Breaking Changes` section as well. To describe in how to upgrade from one version to another if needed
+
+## [Unreleased]
+### Added
+### Changed
+### Breaking changes
+### Removed
+
+
+
+## [0.1.2] - 2024-11-19
+### Added
+- Added retries with exponential backoff to send transactions in [#158](https://github.com/Layr-Labs/eigensdk-rs/pull/158)
+- Added `query_registration_detail` method in [#162](https://github.com/Layr-Labs/eigensdk-rs/pull/162)
+- Added clippy lints in `Cargo.toml` in [#159](https://github.com/Layr-Labs/eigensdk-rs/pull/159)
+- Added BLS aggregation logger in [#154](https://github.com/Layr-Labs/eigensdk-rs/pull/154)
+- Added `common` crate to `eigensdk` crate in [#213](https://github.com/Layr-Labs/eigensdk-rs/pull/213)
+
+### Changed
+- Updated `eigenlayer-middleware` to v0.4.3 (rewards release) in [#177](https://github.com/Layr-Labs/eigensdk-rs/pull/177)
+- Fixed Holesky RPC provider URL in [#184](https://github.com/Layr-Labs/eigensdk-rs/pull/184)
+- Fixed BLS signature logic in [#174](https://github.com/Layr-Labs/eigensdk-rs/pull/174)
+
+### Removed
+- Deleted `TxManager` in [#151](https://github.com/Layr-Labs/eigensdk-rs/pull/151)
+- Removed `TxManager` crate import in [#211](https://github.com/Layr-Labs/eigensdk-rs/pull/211)
+- Removed logs in `operatorsinfo` test in [#185](https://github.com/Layr-Labs/eigensdk-rs/pull/185)
+
+### Documentation
+- Added notes for running tests in [#194](https://github.com/Layr-Labs/eigensdk-rs/pull/194)
+- Added "Contract Bindings" section to the README in [#178](https://github.com/Layr-Labs/eigensdk-rs/pull/178)
+- Added "Branches" section to the README in [#200](https://github.com/Layr-Labs/eigensdk-rs/pull/200)