Update git submodules

Update git submodules

* Update docs/submodules/functest from branch 'stable/euphrates'
  - Merge changes I17d45782,I008cf0f5 into stable/euphrates

    * changes:
      Suggest to pull manifests instead of arch tags
      Update release notes for Euphrates 5.1

  - Suggest to pull manifests instead of arch tags

    Change-Id: I17d45782feb38946f9524859354f24d392b56f25
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>
    (cherry picked from commit 00a39f80a318d75360e48190e547afe33ca3e01a)

  - Update release notes for Euphrates 5.1

    Change-Id: I008cf0f5cd5279903d7e50b5a3903c283829e9cb
    Signed-off-by: Jose Lausuch <jalausuch@suse.com>
    (cherry picked from commit 4470868c2d4486e8dbfab925c22eb364974b2c40)