docs: fix a typo in the glossary

Signed-off-by: Sandrine Bailleux <sandrine.bailleux@arm.com>
Change-Id: I4c76fde5e487ab4b2495f1ea692ae07f8be81d57
diff --git a/docs/glossary.rst b/docs/glossary.rst
index 57fde2d..12c6ab7 100644
--- a/docs/glossary.rst
+++ b/docs/glossary.rst
@@ -229,7 +229,7 @@
       Trusted Platform Module
 
    TRNG
-      True Randon Number Generator (hardware based)
+      True Random Number Generator (hardware based)
 
    TSP
       Test Secure Payload