Updated git submodules

Project: dcaegen2 beijing 7ac8d24169dbc135ae6856e495e2bd5465fa8cbf

Update default branch to beijing

Issue-ID: DCAEGEN2-516
Change-Id: I9ea40aba41c6c4ec555f57fc963c5a21da669976
Signed-off-by: Lusheng Ji <lji@research.att.com>
Fix doc build warnings

Issue-ID: DCAEGEN2-516
Change-Id: I94f1c7fcf5e4a21752c3ce9d8d71d98f2140e1ee
Signed-off-by: Lusheng Ji <lji@research.att.com>
Update release notes.
Update documentations.

Issue-ID: DCAEGEN2-499
Change-Id: Ib315a444678ff73e85f2c7e212eab44037b59b02
Signed-off-by: Lusheng Ji <lji@research.att.com>

diff --git a/docs/submodules/dcaegen2.git b/docs/submodules/dcaegen2.git
index 82799c7..7ac8d24 160000 (submodule)
--- a/docs/submodules/dcaegen2.git
+++ b/docs/submodules/dcaegen2.git
@@ -1 +1 @@
-Subproject commit 82799c75a86263926feb6369a0f2ac9cf76a6ec7
+Subproject commit 7ac8d24169dbc135ae6856e495e2bd5465fa8cbf