doc: Clarify draft status of SPCI and SPRT specs

These SPM-related specifications are mentioned in the readme and
the change log. Update references to these specs to make it clear
that they are in draft form and are expected to change.

Change-Id: Ia2791c48c371a828246d96f102a402747cd69f96
Signed-off-by: Paul Beesley <paul.beesley@arm.com>
diff --git a/readme.rst b/readme.rst
index bfec591..41ffc0f 100644
--- a/readme.rst
+++ b/readme.rst
@@ -139,7 +139,7 @@
    in read-write memory, allowing for the library code to be patched.
 
 -  A prototype implementation of a Secure Partition Manager (SPM) that is based
-   on the SPCI and SPRT specifications.
+   on the SPCI Alpha 1 and SPRT draft specifications.
 
 -  Support for ARMv8.3 pointer authentication in the normal and secure worlds.
    The use of pointer authentication in the normal world is enabled whenever
@@ -239,7 +239,8 @@
 
 -  Refinements to Position Independent Executable (PIE) support.
 
--  Refinements to SPCI-compliant SPM implementation.
+-  Refinements to the SPCI-based SPM implementation as the draft SPCI and SPRT
+   specifications continue to evolve.
 
 -  Documentation enhancements.