DOC: Fix typo in merging.rst (pandas-dev#57242)

Fix typo in merging.rst

Author: thadguidry

doc/source/user_guide/merging.rst

@@ -249,7 +249,7 @@ a :class:`MultiIndex`) associate specific keys with each original :class:`DataFr
    p.plot(frames, result, labels=["df1", "df2", "df3"], vertical=True)
    plt.close("all");
 
-The ``keys`` argument cane override the column names
+The ``keys`` argument can override the column names
 when creating a new :class:`DataFrame` based on existing :class:`Series`.
 
 .. ipython:: python