fix typo

Author: stephenworsley

src/esmf_regrid/experimental/partition.py

@@ -99,7 +99,7 @@ def __init__(
         ----
         The source is partitioned into blocks using one of the four mutually exclusive arguments,
         `use_dask_src_chunks`, `src_chunks`, `num_src_chunks`, or `explicit_src_blocks`. These
-        describe a partition into a numnber of blocks which must equal the number of `file_names`.
+        describe a partition into a number of blocks which must equal the number of `file_names`.
 
         Currently, it is only possible to divide the source grid into chunks.
         Meshes are not yet supported as a source.