Update git submodules

* Update docs/submodules/copper from branch 'master'
  - Local Documentation Builds

        This adds configuration for performing local documentation builds
        with the following simple command:

        tox -e docs

    Change-Id: I8f472b3f2fd6f5fbad97a728166b17f33cf5cb24
    Signed-off-by: Aric Gardner <agardner@linuxfoundation.org>

diff --git a/docs/submodules/copper b/docs/submodules/copper
index 2527488..505dc77 160000 (submodule)
--- a/docs/submodules/copper
+++ b/docs/submodules/copper
@@ -1 +1 @@
-Subproject commit 2527488ab77d7e4e4471402e657f5b4752fb6e56
+Subproject commit 505dc7754239feaa28c736abb3019598db2a1a56