Update git submodules

Update git submodules

* Update docs/submodules/vnfsdk/model.git from branch 'master'
  to 2d314a01d7f46ccefc18b89f9b661ff15bccc0d7
  - documents have different spelling mistakes and grammatical issues

    fix for documents mistakes

    Issue-ID: VNFSDK-448

    Signed-off-by: anjali.walsatwar <anjali.walsatwar@huawei.com>
    Change-Id: I94771e0b2bf87acc929824c3fc68ca7b47cf004d

  - documents have different spelling mistakes and grammatical issues

    fix for documents mistakes

    Issue-ID: VNFSDK-448

    Signed-off-by: anjali.walsatwar <anjali.walsatwar@huawei.com>
    Change-Id: If2b2eabf8e4853fac2e283f8e55e5b31b404bf0d

  - documents have different spelling mistakes and grammatical issues

    fix for documents mistakes

    Issue-ID: VNFSDK-448

    Signed-off-by: anjali.walsatwar <anjali.walsatwar@huawei.com>
    Change-Id: I5b4863ca1830fa24d5b2ba02b7f8d3b1884a80f7