Update git submodules

* Update docs/submodules/msb/discovery.git from branch 'master'
  to a900b81fc5a962c5037f485960dbeea70311154f
  - fix maven-dockera-stage build error
    
    Issue-ID: MSB-373
    Signed-off-by: Huabing Zhao <zhao.huabing@zte.com.cn>
    Change-Id: I570361b1e646fab8f9abbfc770ddb6ba3d05cca4
    
diff --git a/docs/submodules/msb/discovery.git b/docs/submodules/msb/discovery.git
index 0f982ec..a900b81 160000
--- a/docs/submodules/msb/discovery.git
+++ b/docs/submodules/msb/discovery.git
@@ -1 +1 @@
-Subproject commit 0f982ec9d1c6a0486cc7ee366ecc05cda2d1cfc3
+Subproject commit a900b81fc5a962c5037f485960dbeea70311154f