Improve MSSQL documentation to describe how to use Windows auth with MS SQL.

Setup docs for SQL server don't describe how to use Windows auth with MS SQL. Starting from Confluence 6.4.0 bundled the JDBC driver does support logging in with a domain account rather than a SQL Server user but clear instructions are not in the docs.

Can documentation be improved by adding this information?

Referring documentation:

• https://jira.atlassian.com/browse/CONFSERVER-26834
• https://docs.microsoft.com/en-us/sql/connect/jdbc/building-the-connection-url#Connectingintegrated