Doc: Removed TF-M prefix from document heading

This patch removes the TF-M/Trusted Firmware prefix from the
title heading across the documentation.

Change-Id: I60e0c6e48615f67ee040a0d6dbc7d6f1873856e7
Signed-off-by: Galanakis, Minos <minos.galanakis@arm.com>
diff --git a/docs/design_documents/tfm_crypto_design.rst b/docs/design_documents/tfm_crypto_design.rst
index c0cf769..a8e260d 100644
--- a/docs/design_documents/tfm_crypto_design.rst
+++ b/docs/design_documents/tfm_crypto_design.rst
@@ -1,5 +1,5 @@
-TF-M Crypto Service design
-==========================
+Crypto Service design
+=====================
 
 :Author: Antonio de Angelis
 :Organization: Arm Limited