Hi,

There is something out of fashion in the first version SPRTL document, and the content is not well-formatted in a not ideal place. I updated parts of the document:

- Re-format the document. - Fixes the descriptions for C runtime API, now we are re-using the headers, types and parts of toolchain library if possible. - Important change: Define a new 'SP Scratch' area and needs SPM cooperation to let the SPRTL can retrieve SP specific metadata.

The new SP scratch area is used for resolving the context-based runtime API cannot retrieve the SP metadata problem since SPRTL is just a code. With this change, the SPRTL has a way to retrieve the SP metadata and then context-based runtime API is much easier in implementation.

The patch is here: https://review.trustedfirmware.org/c/trusted-firmware-m/+/3457 And the issue: https://developer.trustedfirmware.org/T484

Thanks.

/Ken