Update git submodules

Update git submodules

* Update docs/submodules/daisy from branch 'master'
  - Jira: DAISY-36 Update doc structure

    This PS update doc structure according to [1].

    Note: This PS also add content to doc for describing the
    mapping methods for map role to discovered nodes.

    [1] http://docs.opnfv.org/en/stable-danube/how-to-use-docs/documentation-guide.html?highlight=templates#document-structure-and-contribution

    Change-Id: I7b2ef916753cddd8cd845abae8c7d5865c49e1ac
    Signed-off-by: Zhijiang Hu <hu.zhijiang@zte.com.cn>