Update git submodules

Update git submodules

* Update docs/submodules/oom.git from branch 'master'
  to 23756ac9a30c9dd391c6cb8a7bfa44fc780fa0c4
  - Merge "[DOC] Add a link to index"
  - [DOC] Add a link to index

    New documentation generation system relies on disjoint documentations.
    This patch adds an label for OOM main index with name being consistent
    accross all ONAP components.

    Issue-ID: CIMAN-376
    Change-Id: I1c13b2c478857c45a30ec5e5fb4881934e6f70f3
    Signed-off-by: lf-jobbuilder <releng+lf-jobbuilder@linuxfoundation.org>
    Signed-off-by: Sylvain Desbureaux <sylvain.desbureaux@orange.com>