Expand documentation on how batches are executed

moor/lib/src/runtime/api/batch.dart

@@ -40,6 +40,8 @@ class Batch {
   /// By default, an exception will be thrown if another row with the same
   /// primary key already exists. This behavior can be overridden with [mode],
   /// for instance by using [InsertMode.replace] or [InsertMode.insertOrIgnore].
+  /// Using [insertAll] will not disable primary keys or any column constraint
+  /// checks.
   void insertAll<D extends DataClass>(
       TableInfo<Table, D> table, List<Insertable<D>> rows,
       {InsertMode mode}) {

moor/lib/src/runtime/api/query_engine.dart

@@ -258,7 +258,7 @@ mixin QueryEngine on DatabaseConnectionUser {
   /// A batch can only run a subset of statements, and those statements must be
   /// called on the [Batch] instance. The statements aren't executed with a call
   /// to [Batch]. Instead, all generated queries are queued up and are then run
-  /// and executed atomically.
+  /// and executed atomically in a transaction.
   /// Typically, running bulk updates (so a lot of similar statements) over a
   /// [Batch] is much faster than running them via the [GeneratedDatabase]
   /// directly.