Remove TF-M prefix on base folders

This patch removes the 'TF-M' prefix for those doc snippets referring
to the base folder, which is the folder where all TF-M related
repositories reside. With this change, there are now two different
type of base folders on the documentation:

* '<base folder>' is the base folder of all TF-M related repositories,
i.e. '~/TF'

* '<TF-M base folder>' is the base folder of trusted-firmware-m
repository, .i.e '~/TF/trusted-firmware-m'

Change-Id: Ib2d61bfafb337a36a4b0e98b25bac2d4079768c2
Signed-off-by: Leonardo Sandoval <leonardo.sandoval@linaro.org>
diff --git a/docs/reference/services/tfm_secure_partition_addition.rst b/docs/reference/services/tfm_secure_partition_addition.rst
index 774220a..ec40b79 100644
--- a/docs/reference/services/tfm_secure_partition_addition.rst
+++ b/docs/reference/services/tfm_secure_partition_addition.rst
@@ -315,7 +315,7 @@
 
 .. code-block:: bash
 
-   cd <TF-M base folder>
+   cd <base folder>
    cd trusted-firmware-m
    python ./tools/tfm_parse_manifest_list.py