No documentation or release notes for v6.4.12

[DFEvans]

Describe the bug
notebook v6.4.12 was released last week, and is now being highlighted by Github's dependabot as a security fix. However, it is unclear from the documentation v6.4.12 has been released, and what changes it contains, because:

• There is no v6.4.12 tag in the repo, only v6.4.11
• The changelog in the documentation does not indicate that v6.4.12 exists.

The same issue affects v6.4.10.

Expected behavior
Information about v6.4.12, and the security fixes within it, should be easily locatable.

[jtpio]

Thanks @DFEvans for reporting.

This will likely be fixed by #6452.

[jtpio]

Closing as fixed by #6452