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/user_guides/tfm_build_instruction.rst b/docs/user_guides/tfm_build_instruction.rst
index 33aefd7..52e52a5 100644
--- a/docs/user_guides/tfm_build_instruction.rst
+++ b/docs/user_guides/tfm_build_instruction.rst
@@ -1,6 +1,6 @@
-######################
-TF-M build instruction
-######################
+##################
+Build instructions
+##################
 Please make sure you have all required software installed as explained in the
 :doc:`software requirements <tfm_sw_requirement>`.