add existing major features

FEATURES.md

@@ -0,0 +1,18 @@
+# Features
+
+The following table indicates the major ICS features available in the [currently active releases](./RELEASES.md#version-matrix):
+
+| Feature | Release | `v1.2.0-multiden` | `v2.0.0` | `v2.1.0-provider-lsm` | `v2.4.0-lsm` | `v3.1.0` |
+|---------|---------|------------------:|---------:|----------------------:|-------------:|---------:|
+| [Channel initialization: new chains](https://github.com/cosmos/ibc/blob/main/spec/app/ics-028-cross-chain-validation/overview_and_basic_concepts.md#channel-initialization-new-chains) | | ✅ | ✅ | ✅ | ✅ | ✅ | 
+| [Validator set update](https://github.com/cosmos/ibc/blob/main/spec/app/ics-028-cross-chain-validation/overview_and_basic_concepts.md#validator-set-update) | | ✅ | ✅ | ✅ | ✅ | ✅ | 
+| [Completion of unbonding operations](https://github.com/cosmos/ibc/blob/main/spec/app/ics-028-cross-chain-validation/overview_and_basic_concepts.md#completion-of-unbonding-operations) | | ✅ | ✅ | ✅ | ✅ | ✅ | 
+| [Consumer initiated slashing](https://github.com/cosmos/ibc/blob/main/spec/app/ics-028-cross-chain-validation/overview_and_basic_concepts.md#consumer-initiated-slashing) | | ✅ | ✅ | ✅ | ✅ | ✅ | 
+| [Reward distribution](https://github.com/cosmos/ibc/blob/main/spec/app/ics-028-cross-chain-validation/overview_and_basic_concepts.md#reward-distribution) | | ✅ | ✅ | ✅ | ✅ | ✅ | 
+| [Consumer chain removal](https://github.com/cosmos/ibc/blob/main/spec/app/ics-028-cross-chain-validation/methods.md#consumer-chain-removal) | | ✅ | ✅ | ✅ | ✅ | ✅ | 
+| [Key assignment](https://github.com/cosmos/interchain-security/issues/26) | | ✅ | ✅ | ✅ | ✅ | ✅ | 
+| [Jail throttling](https://github.com/cosmos/interchain-security/issues/404) | | ✅ | ✅ | ✅ | ✅ | ✅ | 
+| [Soft opt-out](https://github.com/cosmos/interchain-security/issues/851) | | ✅ | ✅ | ✅ | ✅ | ✅ | 
+| [Channel initialization: existing chains](https://github.com/cosmos/ibc/blob/main/spec/app/ics-028-cross-chain-validation/overview_and_basic_concepts.md#channel-initialization-existing-chains) (aka [Standalone to consumer changeover](https://github.com/cosmos/interchain-security/issues/756))| | ❌ | ✅ | ✅ | ✅ | ✅ | 
+| [Cryptographic verification of equivocation](https://github.com/cosmos/interchain-security/issues/732) | | ❌ | ❌ | ❌ | ✅ | ❌ | 
+

README.md

@@ -9,7 +9,11 @@
 
 **interchain-security** contains a working and in-production implementation of the Replicated Security protocol (aka Interchain Security V1). Replicated security is an open sourced IBC application which allows cosmos blockchains to lease their proof-of-stake security to one another.
 
-For more details on the Replicated Security protocol, take a look at the [docs](https://cosmos.github.io/interchain-security/) or [technical specification](https://github.com/cosmos/ibc/blob/main/spec/app/ics-028-cross-chain-validation/README.md).
+For more details on the **Replicated Security protocol**, take a look at the [docs](https://cosmos.github.io/interchain-security/) or [technical specification](https://github.com/cosmos/ibc/blob/main/spec/app/ics-028-cross-chain-validation/README.md).
+
+For a list of **currently active releases**, see [RELEASES.md](./RELEASES.md#version-matrix).
+
+For a list of **major ICS features** available in the currently active releases, see [FEATURES.md](./FEATURES.md).
 
 ## Instructions
 

RELEASES.md

@@ -84,13 +84,15 @@ Versions of Golang, IBC, Cosmos SDK and CometBFT used by ICS in the currently ac
 | [v2.4.0-lsm](https://github.com/cosmos/interchain-security/releases/tag/v2.4.0-lsm) | 1.19 | v4.4.2 | v0.45.16-ics-lsm | v0.34.28 | Provider only (Cosmos Hub specific) |
 | [v3.1.0](https://github.com/cosmos/interchain-security/releases/tag/v3.1.0) | 1.20 | v7.1.0 | v0.47.3 | v0.37.2 |
 
+**Note:** For a list of major ICS features available in the currently active releases, see [FEATURES.md](./FEATURES.md).
+
 ### Backwards Compatibility
 
 A MAJOR version of ICS will always be backwards compatible with the previous MAJOR version of ICS. 
 
 The following table indicates the compatibility of currently active releases:
 
-| consumer | provider | `v2.0.0` | `v2.1.0-provider-lsm` | `v2.4.0-lsm` | `v3.1.0` |
+| Consumer | Provider | `v2.0.0` | `v2.1.0-provider-lsm` | `v2.4.0-lsm` | `v3.1.0` |
 |----------|----------|--------:|----------------------:|----------------------:|---------:|
 | `v1.2.0-multiden` || ✅ | ✅ | ✅ | ✅ | 
 | `v2.0.0` || ✅ | ✅ | ✅ | ✅ |