docs: add v2.0.0-lsm changelog section (#1210)

add changelog section

Author: mpoke

CHANGELOG.md

@@ -4,6 +4,10 @@
 
 Add an entry to the unreleased section whenever merging a PR to main that is not targeted at a specific release. These entries will eventually be included in a release.
 
+## v2.0.0-lsm
+
+Date: August 16th, 2023
+
 * (deps!) [#1120](https://github.com/cosmos/interchain-security/pull/1120) Bump [Cosmos SDK](https://github.com/cosmos/cosmos-sdk) to [v0.45.16-ics-lsm](https://github.com/cosmos/cosmos-sdk/tree/v0.45.16-ics-lsm). This requires adapting ICS to support this SDK release. Changes are state breaking.
 * (fix) [#720](https://github.com/cosmos/interchain-security/issues/720) Fix the attribute `AttributeDistributionTotal` value in `FeeDistribution` event emit.