Update example

Author: BenConstable9

text_2_sql/.env.example

@@ -1,5 +1,7 @@
 # Environment variables for Text2SQL
 IdentityType=<identityType> # system_assigned or user_assigned or key
+
+Text2Sql__DatabaseEngine=<DatabaseEngine> # TSQL or PostgreSQL or Snowflake or Databricks
 Text2Sql__UseQueryCache=<Determines if the Query Cache will be used to speed up query generation. Defaults to True.> # True or False
 Text2Sql__PreRunQueryCache=<Determines if the results from the Query Cache will be pre-run to speed up answer generation. Defaults to True.> # True or False
 Text2Sql__UseColumnValueStore=<Determines if the Column Value Store will be used for schema selection Defaults to True.> # True or False