Contracts: Remove changelog (#3605)

This is not maintained, and we should be able to get information
from the release changelog

substrate/frame/contracts/CHANGELOG.md

-# 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).
-
-The semantic versioning guarantees cover the interface to the Substrate runtime which
-includes this pallet as a dependency. This module will also add storage migrations whenever
-changes require it. Stability with regard to offchain tooling is explicitly excluded from
-this guarantee: For example adding a new field to an in-storage data structure will require
-changes to frontends to properly display it. However, those changes will still be regarded
-as a minor version bump.
-
-The interface provided to smart contracts will adhere to semver with one exception: Even
-major version bumps will be backwards compatible with regard to already deployed contracts.
-In other words: Upgrading this pallet will not break pre-existing contracts.
-
-## [Unreleased]
-
-### Added
-
-- Forbid calling back to contracts after switching to runtime
-[#13443](https://github.com/paritytech/substrate/pull/13443)
-
-- Allow contracts to dispatch calls into the runtime (**unstable**)
-[#9276](https://github.com/paritytech/substrate/pull/9276)
-
-- New version of `seal_call` that offers more features.
-[#8909](https://github.com/paritytech/substrate/pull/8909)
-
-- New `instantiate` RPC that allows clients to dry-run contract instantiation.
-[#8451](https://github.com/paritytech/substrate/pull/8451)
-
-- New version of `seal_random` which exposes additional information.
-[#8329](https://github.com/paritytech/substrate/pull/8329)
-
-### Changed
-
-- Replaced storage rent with automatic storage deposits
-[#9669](https://github.com/paritytech/substrate/pull/9669)
-[#10082](https://github.com/paritytech/substrate/pull/10082)
-
-- Replaced `seal_println` with the `seal_debug_message` API which allows outputting debug
-messages to the console and RPC clients.
-[#8773](https://github.com/paritytech/substrate/pull/8773)
-[#9550](https://github.com/paritytech/substrate/pull/9550)
-
-- Make storage and fields of `Schedule` private to the crate.
-[#8359](https://github.com/paritytech/substrate/pull/8359)
-
-### Fixed
-
-- Remove pre-charging which caused wrongly estimated weights
-[#8976](https://github.com/paritytech/substrate/pull/8976)
-
-## [v3.0.0] 2021-02-25
-
-This version constitutes the first release that brings any stability guarantees (see above).
-
-### Added
-
-- Emit an event when a contract terminates (self-destructs).
-[#8014](https://github.com/paritytech/substrate/pull/8014)
-
-- Charge rent for code stored on the chain in addition to the already existing
-rent that is paid for data storage.
-[#7935](https://github.com/paritytech/substrate/pull/7935)
-
-- Allow the runtime to configure per storage item costs in addition
-to the already existing per byte costs.
-[#7819](https://github.com/paritytech/substrate/pull/7819)
-
-- Contracts are now deleted lazily so that the user who removes a contract
-does not need to pay for the deletion of the contract storage.
-[#7740](https://github.com/paritytech/substrate/pull/7740)
-
-- Allow runtime authors to define chain extensions in order to provide custom
-functionality to contracts.
-[#7548](https://github.com/paritytech/substrate/pull/7548)
-[#8003](https://github.com/paritytech/substrate/pull/8003)
-
-- Proper weights which are fully automated by benchmarking.
-[#6715](https://github.com/paritytech/substrate/pull/6715)
-[#7017](https://github.com/paritytech/substrate/pull/7017)
-[#7361](https://github.com/paritytech/substrate/pull/7361)
-
-### Changed
-
-- Collect the rent for one block during instantiation.
-[#7847](https://github.com/paritytech/substrate/pull/7847)
-
-- Instantiation takes a `salt` argument to allow for easier instantion of the
-same code by the same sender.
-[#7482](https://github.com/paritytech/substrate/pull/7482)
-
-- Improve the information returned by the `contracts_call` RPC.
-[#7468](https://github.com/paritytech/substrate/pull/7468)
-
-- Simplify the node configuration necessary to add this module.
-[#7409](https://github.com/paritytech/substrate/pull/7409)
-
-### Fixed
-
-- Consider the code size of a contract in the weight that is charged for
-loading a contract from storage.
-[#8086](https://github.com/paritytech/substrate/pull/8086)
-
-- Fix possible overflow in storage size calculation
-[#7885](https://github.com/paritytech/substrate/pull/7885)
-
-- Cap the surcharge reward that can be claimed.
-[#7870](https://github.com/paritytech/substrate/pull/7870)
-
-- Fix a possible DoS vector where contracts could allocate too large buffers.
-[#7818](https://github.com/paritytech/substrate/pull/7818)