Move dispatcher documents to the docs/spd folder

This patch moves the optee-dispatcher.md and tlk-dispatcher.md to
docs/spd.

Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>
diff --git a/docs/optee-dispatcher.md b/docs/spd/optee-dispatcher.md
similarity index 100%
rename from docs/optee-dispatcher.md
rename to docs/spd/optee-dispatcher.md
diff --git a/docs/tlk-dispatcher.md b/docs/spd/tlk-dispatcher.md
similarity index 100%
rename from docs/tlk-dispatcher.md
rename to docs/spd/tlk-dispatcher.md