Add doc submodule for MSB swagger sdk

Change-Id: I38c9b7e9ab53be3e5927b07fb52991b24a65f890
Issue-Id: MSB-81
Signed-off-by: HuabingZhao <zhao.huabing@zte.com.cn>
diff --git a/.gitmodules b/.gitmodules
index 4bdb2c0..92d9937 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -77,3 +77,6 @@
 [submodule "docs/submodules/msb/java-sdk.git"]
 	path = docs/submodules/msb/java-sdk.git
 	url = ../msb/java-sdk
+[submodule "docs/submodules/msb/swagger-sdk.git"]
+	path = docs/submodules/msb/swagger-sdk.git
+	url = ../msb/swagger-sdk