Update git submodules

Update git submodules

* Update docs/submodules/netready from branch 'stable/danube'
  - Fixing broken links in documentation

    Using rst references to link to other documentation pages
    instead of relative HTML links.

    Change-Id: Id8164a4f50f4fd39c996f5ae354b22f3c960fb08
    Signed-off-by: Georg Kunz <georg.kunz@ericsson.com>
    (cherry picked from commit 0c59ca9234d712a74fa01c1eaba676dfb0080052)

  - Adding further documentation for the Gluon scenario

    Change-Id: I4926ab30223312b91b6349b798f652615d70001e
    Signed-off-by: Georg Kunz <georg.kunz@ericsson.com>
    (cherry picked from commit 8a3e022acdcab14bd1f51cf08f4a26004dda49e7)