fix(migrations): add indicatives comment at start of SQL files

lib/sqlxgentools_cli/src/gen_migrations.rs

@@ -29,6 +29,8 @@ impl Field {
 /// Generate CREATE TABLE statement from parsed model
 pub fn generate_create_table_sql(models: &[Model]) -> Result<String> {
     let mut sql_code: String = "".into();
+    sql_code.push_str("-- DO NOT EDIT THIS FILE.\n");
+    sql_code.push_str("-- Generated by sqlxgentools from models files.\n");
     for model in models.iter() {
         let mut fields_sql: Vec<String> = vec![];
         for field in model.fields.iter() {