Update git submodules

* Update docs/submodules/opera from branch 'stable/danube'
  - doc adjust

    change doc structrue

    Change-Id: I66bea1f0a922930f0407dc04898fbb410d9305e9
    Signed-off-by: Harry Huang <huangxiangyu5@huawei.com>
    (cherry picked from commit 2943208b162c1fc4fc21cae98ec412b476ce95aa)

diff --git a/docs/submodules/opera b/docs/submodules/opera
index d972244..82de7c1 160000 (submodule)
--- a/docs/submodules/opera
+++ b/docs/submodules/opera
@@ -1 +1 @@
-Subproject commit d97224431caa5f1187137f8bd2818d2f5bbaa83e
+Subproject commit 82de7c1f69ad128ee9f60aae271c54dd69fc8c22