chore: Remove duplicate 2.0.0 secion from CHANGELOG

Removed duplicate major changes section from version 2.0.0. (Manually created these for the first ESM/yargs release.)

Author: rossiam

CHANGELOG.md

@@ -2,12 +2,6 @@
 
 ## 2.0.0
 
-### Major Changes
-
-- [#806](https://github.com/SmartThingsCommunity/smartthings-cli/pull/806) [`e9e7552`](https://github.com/SmartThingsCommunity/smartthings-cli/commit/e9e7552e2fa0d014393f19adc496f45f0a2a3678) Thanks [@rossiam](https://github.com/rossiam)! - refactor to use yargs
-
-## 2.0.0
-
 - All commands now have examples in their help (`smartthings <command> --help`).
 - args that require enum-like types are now case-insensitive. e.g. For example, you can now list zigbee
   devices with `smartthings devices --type zigbee`.