fix typos

docs/source/implementation.md

@@ -199,7 +199,7 @@ width: 100%
 1. Group labels must be known at graph construction time, so this only works for numpy arrays.
 1. This does require more tasks and a more complicated graph, but the communication overhead can be significantly lower.
 1. The detection of "cohorts" is currently slow but could be improved.
-1. The extra effort of detecting cohorts and mul;tiple copying of intermediate blocks may be worthwhile only if the chunk sizes are small
+1. The extra effort of detecting cohorts and multiple copying of intermediate blocks may be worthwhile only if the chunk sizes are small
    relative to the approximate period of group labels, or small relative to the size of spatially localized groups.
 
 ### Example : sensitivity to chunking

docs/source/user-stories/custom-aggregations.ipynb

@@ -135,7 +135,7 @@
     "    # The next are for dask inputs and describe how to reduce\n",
     "    # the data in parallel\n",
     "    chunk=(\"sum\", \"nanlen\"), # first compute these blockwise : (grouped_sum, grouped_count)\n",
-    "    combine=(\"sum\", \"sum\"), #  reduce intermediate reuslts (sum the sums, sum the counts)\n",
+    "    combine=(\"sum\", \"sum\"), #  reduce intermediate results (sum the sums, sum the counts)\n",
     "    finalize=lambda sum_, count: sum_ / count, # final mean value (divide sum by count)\n",
     "\n",
     "    fill_value=(0, 0),  # fill value for intermediate  sums and counts when groups have no members\n",