DOC: escape asterisks

Author: jorisvandenbossche

doc/source/whatsnew/v0.15.2.txt

@@ -58,7 +58,7 @@ Experimental
 
 Bug Fixes
 ~~~~~~~~~
-- Bug in ``groupby`` signatures that didn't include *args or **kwargs (:issue:`8733`).
+- Bug in ``groupby`` signatures that didn't include \*args or \*\*kwargs (:issue:`8733`).
 - ``io.data.Options`` now raises ``RemoteDataError`` when no expiry dates are available from Yahoo and when it receives no data from Yahoo (:issue:`8761`), (:issue:`8783`).
 - Bug in slicing a multi-index with an empty list and at least one boolean indexer (:issue:`8781`)
 - ``io.data.Options`` now raises ``RemoteDataError`` when no expiry dates are available from Yahoo (:issue:`8761`).