Fix typo in header of TLS 1.3 experimental features document

Signed-off-by: Hanno Becker <hanno.becker@arm.com>
diff --git a/docs/architecture/tls13-experimental.md b/docs/architecture/tls13-experimental.md
index ee8452b..0e3c7cc 100644
--- a/docs/architecture/tls13-experimental.md
+++ b/docs/architecture/tls13-experimental.md
@@ -1,4 +1,4 @@
-Experimental TLS 1.3 develpoments
+TLS 1.3 Experimental Developments
 =================================
 
 Overview