docs: migrate documentation and place it under docs

Migrate the TrustedFirmaware Open CI User Guide documentation,
originally hosted at [1] and place it under docs folder so mkdocs
tool, the tool used by [2], can render properly.

[1] https://github.com/dbharbin/TrustedFirmware-OpenCI-Users-Guide
[2] https://docs.readthedocs.io/en/stable/intro/getting-started-with-mkdocs.html

Signed-off-by: Leonardo Sandoval <leonardo.sandoval@linaro.org>
Change-Id: Ib257f287a73fa9bb7aba4b8b045b815b66de9691
diff --git a/mkdocs.yml b/mkdocs.yml
new file mode 100644
index 0000000..67332df
--- /dev/null
+++ b/mkdocs.yml
@@ -0,0 +1 @@
+site_name: TrustedFirmware OpenCI User Guide