Update git submodules

Update git submodules

* Update docs/submodules/externalapi/nbi.git from branch 'master'
  to 78b0ab8c410c9d4c79a98e3a71fe635c028f4785
  - WIP: add embedded ReDoc documentation for API

    Include ReDoc using embedded JavaScript capabilities in RST

    Create a new directory 'redoc' to store
    - <api>.rst to embed RST content for each API
    - <api>.js to store link towards the JSON Swagger file for each API
    - redoc.js to store JS links to render ReDoc

    Modify offeredapis.rst to include a new section

    Issue-ID: EXTAPI-433

    Signed-off-by: Eric Debeau <eric.debeau@orange.com>
    Change-Id: Iaa2430a7d4080ed6f91ec8a3e2d6203319f29425