Scalar Cryptography v1.0.0-rc5

This is a post-public review release for the Scalar Cryptography extension. It includes a small number of clarifying updates around Zkt and the handling of access control to Zkr in the presence of a hypervisor. It is intended to be a fixed version of the specification used by various RISC-V committees for final sign-off, post-public-review / pre-ratification.

Specific changes since v1.0.0-rc4:

• #136 - Clarified the behaviour of Zkt for sequences of instructions.
• #134 - Updated which exceptions are raised in relation to Zkr in the presence of a hypervisor.

Attached to this release is a summary of all feedback we received during the public review process. We'd like to thank everyone who contributed to our public review for their time and attention, and helping to improve our specification. Your efforts were greatly appreciated!