feat(docs): add DPE to RSE desing doc

Signed-off-by: Tamas Ban <tamas.ban@arm.com>
Change-Id: Iec38be8a3eb93a54d9b5bc7db7a7ff8c126920ac
diff --git a/docs/global_substitutions.txt b/docs/global_substitutions.txt
index ade510d..23a91cd 100644
--- a/docs/global_substitutions.txt
+++ b/docs/global_substitutions.txt
@@ -8,6 +8,8 @@
 .. |COT| replace:: :term:`COT`
 .. |CSS| replace:: :term:`CSS`
 .. |CVE| replace:: :term:`CVE`
+.. |DICE| replace:: :term:`DICE`
+.. |DPE| replace:: :term:`DPE`
 .. |DTB| replace:: :term:`DTB`
 .. |DS-5| replace:: :term:`DS-5`
 .. |DSU| replace:: :term:`DSU`