Changelog for v6.4.0 (#1161)

This is an automated changelog update for v6.4.0

---------

Co-authored-by: Jacob Pleiness <jacob.pleiness@sourcegraph.com>

Author: sourcegraph-bot-devx

docs/releases.mdx

@@ -12,6 +12,7 @@ Currently supported versions of Sourcegraph:
 
 | **Release**  | **General Availability Date** | **Supported** | **Release Notes**                                                  | **Install**                                          |
 |--------------|-------------------------------|---------------|--------------------------------------------------------------------|------------------------------------------------------|
+| 6.4 Patch 0  | May 2025                      | ✅             | [Notes](https://sourcegraph.com/docs/technical-changelog#v640)     | [Install](https://sourcegraph.com/docs/admin/deploy) |
 | 6.3 Patch 2  | May 2025                      | ✅             | [Notes](https://sourcegraph.com/docs/technical-changelog#v634167)  | [Install](https://sourcegraph.com/docs/admin/deploy) |
 | 6.3 Patch 1  | May 2025                      | ✅             | [Notes](https://sourcegraph.com/docs/technical-changelog#v632692)  | [Install](https://sourcegraph.com/docs/admin/deploy) |
 | 6.3 Patch 0  | April 2025                    | ✅             | [Notes](https://sourcegraph.com/docs/technical-changelog#v630)     | [Install](https://sourcegraph.com/docs/admin/deploy) |