SNOW-974746 document that we currently do not support bind variables …

…in multi-statement queries (#819)

re: SNOW-974746 / #817 
document that we currently do not support bind variables in
multi-statement queries, we're getting issues related to this

document-only change, based on
https://docs.snowflake.com/en/developer-guide/sql-api/submitting-multiple-statements#specifying-multiple-sql-statements-in-the-request
which sems to be valid for all the drivers

README.md

@@ -512,6 +512,8 @@ With version 2.0.18 and later of the .NET connector, you can send
 a batch of SQL statements, separated by semicolons,
 to be executed in a single request.
 
+**Note**: Snowflake does not currently support variable binding in multi-statement SQL requests.
+
 ---
 **Note**
 
@@ -579,6 +581,8 @@ using (DbCommand cmd = conn.CreateCommand())
 Bind Parameter
 --------------
 
+**Note**: Snowflake does not currently support variable binding in multi-statement SQL requests.
+
 This example shows how bound parameters are converted from C# data types to
 Snowflake data types. For example, if the data type of the Snowflake column
 is INTEGER, then you can bind C# data types Int32 or Int16.