Update CONTRIBUTING.md (#367)

Author: mShan0

CONTRIBUTING.md

@@ -11,7 +11,7 @@ After changes made to the project, it's a good idea to run the unit tests before
    Download and install SQL Server [here](https://www.microsoft.com/en-us/sql-server/sql-server-downloads), or you could use docker. Change `testapp/settings.py` to match your SQL Server login username and password.  
 
    ```
-   docker run -e 'ACCEPT_EULA=Y' -e 'SA_PASSWORD=MyPassword42' -p 1433:1433 -d mcr.microsoft.com/mssql/server:2019-latest
+   docker run -e 'ACCEPT_EULA=Y' -e 'SA_PASSWORD=Placeholder' -p 1433:1433 -d mcr.microsoft.com/mssql/server:2019-latest
    ```
 2. **Clone Django**   
    In `mssql-django` folder. 
@@ -45,4 +45,4 @@ provided by the bot. You will only need to do this once across all repos using o
 
 This project has adopted the [Microsoft Open Source Code of Conduct](https://opensource.microsoft.com/codeofconduct/).
 For more information see the [Code of Conduct FAQ](https://opensource.microsoft.com/codeofconduct/faq/) or
-contact [opencode@microsoft.com](mailto:opencode@microsoft.com) with any additional questions or comments.
+contact [opencode@microsoft.com](mailto:opencode@microsoft.com) with any additional questions or comments.