chore(cosmovisor): updating changelog (#10019)

<!--
The default pull request template is for types feat, fix, or refactor.
For other templates, add one of the following parameters to the url:
- template=docs.md
- template=other.md
-->

## Description

Adding missing entry to the changelog 



---

### Author Checklist

*All items are required. Please add a note to the item if the item is not applicable and
please add links to any relevant follow up issues.*

I have...

- [ ] included the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] added `!` to the type prefix if API or client breaking change
- [ ] targeted the correct branch (see [PR Targeting](https://github.com/cosmos/cosmos-sdk/blob/master/CONTRIBUTING.md#pr-targeting))
- [ ] provided a link to the relevant issue or specification
- [ ] followed the guidelines for [building modules](https://github.com/cosmos/cosmos-sdk/blob/master/docs/building-modules)
- [ ] included the necessary unit and integration [tests](https://github.com/cosmos/cosmos-sdk/blob/master/CONTRIBUTING.md#testing)
- [ ] added a changelog entry to `CHANGELOG.md`
- [ ] included comments for [documenting Go code](https://blog.golang.org/godoc)
- [ ] updated the relevant documentation or specification
- [ ] reviewed "Files changed" and left comments if necessary
- [ ] confirmed all CI checks have passed

### Reviewers Checklist

*All items are required. Please add a note if the item is not applicable and please add
your handle next to the items reviewed if you only reviewed selected items.*

I have...

- [ ] confirmed the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] confirmed `!` in the type prefix if API or client breaking change
- [ ] confirmed all author checklist items have been addressed 
- [ ] reviewed state machine logic
- [ ] reviewed API design and naming
- [ ] reviewed documentation is accurate
- [ ] reviewed tests and test coverage
- [ ] manually tested (if applicable)

cosmovisor/CHANGELOG.md

@@ -35,6 +35,14 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 # Changelog
 
+
+## [Unreleased]
+
+## Features
+
++ [\#8590](https://github.com/cosmos/cosmos-sdk/pull/8590) File watcher for cosmovisor. Instead of parsing logs from stdin and stderr, we watch the `<DAEMON_HOME>/data/upgrade-info.json` file updates using polling mechanism.
+
+
 ## v0.1 2021-08-06
 
 This is the first release and we started this changelog on 2021-07-01. See the (README)[https://github.com/cosmos/cosmos-sdk/blob/release/cosmovisor/v0.1.x/cosmovisor/CHANGELOG.md] file for the full list of features.