Fix minor typo (#246)

Co-authored-by: Tom Nicholas <thomas.nicholas@columbia.edu>

README.md

@@ -52,7 +52,7 @@ The approach used here is based on benbovy's [`DatasetNode` example](https://gis
 You can create a `DataTree` object in 3 ways:
 1) Load from a netCDF file (or Zarr store) that has groups via `open_datatree()`.
 2) Using the init method of `DataTree`, which creates an individual node.
-  You can then specify the nodes' relationships to one other, either by setting `.parent` and `.chlldren` attributes,
+  You can then specify the nodes' relationships to one other, either by setting `.parent` and `.children` attributes,
   or through `__get/setitem__` access, e.g. `dt['path/to/node'] = DataTree()`.
 3) Create a tree from a dictionary of paths to datasets using `DataTree.from_dict()`.