[spec] Initial MCTP draft (#36)

Initial middleware/mctp.md draft. This document is still WIP but it is
being open sourced to request feedback from the community.

Signed-off-by: Miguel Osorio <miguelosorio@google.com>

Author: moidx

docs/src/specification/middleware/mctp.md

@@ -0,0 +1,41 @@
+# MCTP
+
+Status: Draft.
+
+MCTP OpenPRoT devices shall support MCTP as the transport for all DMTF
+protocols.
+
+## Versions
+
+The *minimum required* MCTP version is 1.3.1 (DSP0236.) Support for MCTP 2.0.0
+(DSP0256) may be introduced in a future version of this spec.
+
+## Required Bindings
+
+Currently only one binding is *mandatory* in the OpenPRoT specification, though
+this will change in future versions. 1. . MCTP over SMBus (DSP0237, 1.2.0)
+
+## Recommended Bindings
+
+1.  MCTP over I3C (DSP0233, 1.0.1)
+2.  MCTP over PCIe-VDM (DSP0238, 1.2.1)
+    *   Only on platforms utilizing PCIe 6 and up.
+3.  MCTP over USB (DSP0283, 1.0.0)
+
+## Required Commands
+
+1.  Set Endpoint ID
+2.  Get Endpoint ID
+3.  Get MCTP Version Support
+4.  Get Message Type Support
+5.  Get Vendor Defined Message Support
+6.  All commands in the range 0xF0 \- 0xFF
+
+## Optional Commands
+
+1.  All other commands are optional, but may become required in future
+    revisions.
+
+## Development TCP Binding
+
+1.  OpenPRoT will provide a TCP binding for developmental purposes.