Add MSSQL to usage doc

docs/docs/usage.md

@@ -213,6 +213,16 @@ var sequelize = new Sequelize('database', 'username', 'password', {
 })
 ```
 
+### MSSQL
+
+The library for MSSQL is`tedious@^1.7.0` You'll just need to define the dialect:
+ 
+```js   
+var sequelize = new Sequelize('database', 'username', 'password', {
+  dialect: 'mssql'
+})
+```
+
 ## Executing raw SQL queries
 
 As there are often use cases in which it is just easier to execute raw / already prepared SQL queries, you can utilize the function`sequelize.query`.