Docs: Rearrange TF-M building instructions

- move the building instructios to a dedicated folder, reflecting main TOC
- adjust links in the documentation

Signed-off-by: Anton Komlev <anton.komlev@arm.com>
Change-Id: I335de95061938d619a47cd813020121809e1459b
diff --git a/docs/integration_guide/index.rst b/docs/integration_guide/index.rst
index 703c4f7..b68558c 100644
--- a/docs/integration_guide/index.rst
+++ b/docs/integration_guide/index.rst
@@ -23,12 +23,12 @@
 *****************
 How to build TF-M
 *****************
-Follow the :doc:`Build instructions </technical_references/instructions/tfm_build_instruction>`.
+Follow the :doc:`Build instructions </building/tfm_build_instruction>`.
 
 ********************************************************
 How to export files for building non-secure applications
 ********************************************************
-Explained in the :doc:`Build instructions </technical_references/instructions/tfm_build_instruction>`.
+Explained in the :doc:`Build instructions </building/tfm_build_instruction>`.
 
 *************************
 How to add a new platform