[skip e2e]Fix a grammar issue (#14686)

Signed-off-by: Nyanliang567 <yanliang.qiao@zilliz.com>

CONTRIBUTING.md

@@ -143,7 +143,7 @@ $ make fmt
 ### C++ coding style
 
 The C++ coding style used in Milvus generally follows [Google C++ Style Guide](https://google.github.io/styleguide/cppguide.html).
-And we made the following changes based on the guide:
+We made the following changes based on the guide:
 
 - 4 spaces for indentation
 - Adopt .cpp file extension instead of .cc extension