board: purism: add the Purism Librem5 phone

Initial commit of Librem5 u-boot and SPL

Signed-off-by: Angus Ainslie <angus@akkea.ca>
Co-developed-by: Sebastian Krzyszkowiak <sebastian.krzyszkowiak@puri.sm>
Signed-off-by: Sebastian Krzyszkowiak <sebastian.krzyszkowiak@puri.sm>
Reviewed-by: Fabio Estevam <festevam@denx.de>
diff --git a/doc/board/purism/index.rst b/doc/board/purism/index.rst
new file mode 100644
index 0000000..a9cdc31
--- /dev/null
+++ b/doc/board/purism/index.rst
@@ -0,0 +1,9 @@
+.. SPDX-License-Identifier: GPL-2.0+
+
+Purism SPC
+==========
+
+.. toctree::
+   :maxdepth: 2
+
+   librem5