docs: prepare v6.4.0 release (#2462)

* add v6.4.0 section to changelog

* upgrading instructions

* release notes

.changelog/v6.4.0/summary.md

@@ -0,0 +1 @@
+*January 7, 2025*

RELEASE_NOTES.md

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-<!--
-  A release notes template that should be adapted for every release
-    - release: <v*.*.*>
-    - release branch: <v*.x>
-    - the last release: <v-last> 
-    - the last release branch: <v-last.x>
--->
-
-# Interchain Security <v*.*.*>  Release Notes
-
-<!--
-  Please indicate whether this release is relevant to consumers or providers.
--->
-❗ ***Note this release is ONLY relevant to <consumers/providers>***
+# Interchain Security v6.4.0 Release Notes
 
 ## 📝 Changelog
-** REMOVE THE LINE BELOW TO ENABLE THE MARKDOWN LINK CHECKER FOR RELEASE **
-<!-- markdown-link-check-disable -->
 
-Check out the [changelog](https://github.com/cosmos/interchain-security/blob/<v*.*.*>/CHANGELOG.md) for a list of relevant changes or [compare all changes](https://github.com/cosmos/interchain-security/compare/<v-last>...<v*.*.*>) from last release.
+Check out the [changelog](https://github.com/cosmos/interchain-security/blob/v6.4.0/CHANGELOG.md) for a list of relevant changes or [compare all changes](https://github.com/cosmos/interchain-security/compare/v6.3.0...v6.4.0) from last release.
 
-<!-- Add the following line for major or minor releases -->
-Refer to the [upgrading guide](https://github.com/cosmos/interchain-security/blob/release/<v*.x>/UPGRADING.md) when migrating from `<v-last.x>` to `<v*.x>`.
+Refer to the [upgrading guide](https://github.com/cosmos/interchain-security/blob/release/v6.4.x/UPGRADING.md) when migrating from `v6.3.x` to `v6.4.x`.
 
-** REMOVE THE LINE BELOW TO ENABLE THE MARKDOWN LINK CHECKER FOR RELEASE **
-<!-- markdown-link-check-enable -->
 ## 🚀 Highlights
 
 <!-- Add any highlights of this release -->
 
-## ❤️ Contributors
-<!-- markdown-link-check-disable -->
-* Informal Systems ([@informalinc](https://twitter.com/informalinc))
-<!-- markdown-link-check-enable -->
+This is a major ICS release that brings a series of improvements to both provider and consumer chains. 
+
+- Remove the `VSCMaturedPackets` from the consumer module (as per [ADR 018](https://cosmos.github.io/interchain-security/adrs/adr-018-remove-vscmatured#consumer-changes-r2)). 
+- Add a priority list to the power shaping parameters. 
+- Remove the governance proposal whitelisting from consumer chains. 
+- Enable the chain ID of a consumer chain to be updated after creation, but before launch. 
+- Enable querying the provider module for the genesis time for a consumer chain. 
+- Enable consumer chains to have customizable slashing and jailing (as per [ADR 020](https://cosmos.github.io/interchain-security/adrs/adr-020-cutomizable_slashing_and_jailing)). 
+- Simplify the changeover from standalone to consumer chains by reusing the existing IBC connection to the provider.
 
-This list is non-exhaustive and ordered alphabetically.  
-Thank you to everyone who contributed to this release!
+In addition to the above improvements, this release also adds [interchain tests](https://github.com/strangelove-ventures/interchaintest) to ICS. This is an effort to simplify the testing framework and increase the confidence of ICS releases.

UPGRADING.md

@@ -1,10 +1,10 @@
 # Upgrading Interchain Security
 
-## Unreleased
+## v6.4.x
 
 ### Provider
 
-Upgrading a provider from v6.2.0 requires state migrations. The following migrators should be added to the upgrade handler of the provider chain:
+Upgrading a provider from `v6.2.x / v6.3.x` requires state migrations. The following migrators should be added to the upgrade handler of the provider chain:
 
 ```golang
 // Initializes infraction parameters for each active consumer. During slashing and jailing of validators for misbehavior on the consumer chain, the parameters defined for that specific consumer will be used. Initially, default values are set, which can later be customized for each consumer as needed.