docs: Decouple refrences from /docs folder

Signed-off-by: Anton Komlev <anton.komlev@arm.com>
Change-Id: I1955201382074eb9e6dd80aadbc456eb09aecb22
diff --git a/docs/contributing/tfm_design_proposal_guideline.rst b/docs/contributing/tfm_design_proposal_guideline.rst
index 14f3804..9e7dfa0 100755
--- a/docs/contributing/tfm_design_proposal_guideline.rst
+++ b/docs/contributing/tfm_design_proposal_guideline.rst
@@ -111,7 +111,7 @@
 
 .. [3] `TF-M gerrit <https://review.trustedfirmware.org/q/project:TF-M/trusted-firmware-m>`_
 
-.. [4] :doc:`Contributing process </docs/contributing/contributing_process>`
+.. [4] :doc:`Contributing process </contributing/contributing_process>`
 
 -------------------