Add libpsa to documentation

Adding libpsa related changes to the documentation.

Signed-off-by: Gabor Toth <gabor.toth2@arm.com>
Change-Id: I551acdf2da43cfd00030f33a1abab8e5754301a2
diff --git a/docs/project/versioning_policy.rst b/docs/project/versioning_policy.rst
index c176db3..0d1352e 100644
--- a/docs/project/versioning_policy.rst
+++ b/docs/project/versioning_policy.rst
@@ -29,7 +29,8 @@
 
 The project hosts multiple components which can be used separately and thus need
 compatibility information expressed independently. Such components get a
-dedicated version ID. Examples are :ref:`libs-libsp` and :ref:`libs-libts`.
+dedicated version ID. Examples are :ref:`libs-libsp` :ref:`libs-libts` and
+:ref:`libs-libpsa`.
 
 Components are never released standalone but only part of a TS release. In that
 sense a set of independent component version IDs are assigned to a TS release ID.