docs: list icp index canister

CHANGELOG.md

@@ -6,7 +6,8 @@
 
 ## Features
 
-- expose few types - notably `BlockHeight` - for library `@dfinity/ledger-icp`
+- add support for ICP Index canister to library `@dfinity/ledger-icp`. New `IndexCanister` functions: `accountBalance`.
+- expose few types - notably `BlockHeight` - for library `@dfinity/ledger-icp`.
 - support new fields from swap canister response types: `min_direct_participation_icp_e8s`, `max_direct_participation_icp_e8s` and `neurons_fund_participation`.
 - support new fields in the `CreateServiceNervousSystem` proposal action `maximum_direct_participation_icp`, `minimum_direct_participation_icp` and `neurons_fund_participation`.
 - support new filter field `omit_large_fields` in `list_proposals`.