chore(docs): default for propagate_positions=False

docs/classes.md

@@ -32,7 +32,7 @@ The Lark class accepts a grammar string or file object, and keyword options:
 
 * **keep_all_tokens** - Don't throw away any terminals from the tree (Default=`False`)
 
-* **propagate_positions** - Propagate line/column count to tree nodes, at the cost of performance (default=`True`)
+* **propagate_positions** - Propagate line/column count to tree nodes, at the cost of performance (default=`False`)
 
 * **maybe_placeholders** - The `[]` operator returns `None` when not matched. Setting this to `False` makes it behave like the `?` operator, and return no value at all, which may be a little faster (default=`True`)