Docs: Update TF-M repository reference

The TF-M repository has been moved from
  git.trustedfirmware.org/trusted-firmware-m to
  git.trustedfirmware.org/TF-M/trusted-firmware-m

This patch updates references to the documentation
to reflect that change.

Signed-off-by: Minos Galanakis <minos.galanakis@arm.com>

Change-Id: Ib7d4d45bae7790bf69fcad4fd16f558716b20d92
diff --git a/docs/processes/tfm_design_proposal_process.rst b/docs/processes/tfm_design_proposal_process.rst
index b72078e..4dfcce1 100644
--- a/docs/processes/tfm_design_proposal_process.rst
+++ b/docs/processes/tfm_design_proposal_process.rst
@@ -102,7 +102,7 @@
   !define REJECTED_DIR **docs/design_documents/rejected/**
   !define GERRIT_URL https://review.trustedfirmware.org
   !define GERRIT_LINK [[GERRIT_URL trustedfirmware.org]]
-  !define MAINTAINER_RST_URL https://git.trustedfirmware.org/trusted-firmware-m.git/tree/docs/maintainers.rst
+  !define MAINTAINER_RST_URL https://git.trustedfirmware.org/TF-M/trusted-firmware-m.git/tree/docs/maintainers.rst
   !define TFM_MAILING_LIST mailto:tf-m@lists.trustedfirmware.org
   !define NO_DECISION **no**
   !define YES_DECISION **yes**