change 'mean' to 'percentile' in doc strings of preprocessor statisti…

…cs (#2327)

Co-authored-by: Manuel Schlund <[email protected]>

esmvalcore/preprocessor/_multimodel.py

@@ -702,8 +702,8 @@ def multi_model_statistics(
     Desired statistics need to be given as a list, e.g., ``statistics: ['mean',
     'median']``. For some statistics like percentiles, it is also possible to
     pass additional keyword arguments, for example ``statistics: [{'operator':
-    'mean', 'percent': 20}]``. A full list of supported statistics is available
-    in the section on :ref:`stat_preprocs`.
+    'percentile', 'percent': 20}]``. A full list of supported statistics is
+    available in the section on :ref:`stat_preprocs`.
 
     This function can handle cubes with differing metadata:
 
@@ -758,9 +758,9 @@ def multi_model_statistics(
     statistics:
         Statistical operations to be computed, e.g., ``['mean', 'median']``.
         For some statistics like percentiles, it is also possible to pass
-        additional keyword arguments, e.g., ``[{'operator': 'mean', 'percent':
-        20}]``. All supported options are are given in :ref:`this table
-        <supported_stat_operator>`.
+        additional keyword arguments, e.g., ``[{'operator': 'percentile',
+        'percent': 20}]``. All supported options are are given in
+        :ref:`this table <supported_stat_operator>`.
     output_products: dict
         For internal use only. A dict with statistics names as keys and
         preprocessorfiles as values. If products are passed as input, the
@@ -845,9 +845,9 @@ def ensemble_statistics(
     statistics:
         Statistical operations to be computed, e.g., ``['mean', 'median']``.
         For some statistics like percentiles, it is also possible to pass
-        additional keyword arguments, e.g., ``[{'operator': 'mean', 'percent':
-        20}]``. All supported options are are given in :ref:`this table
-        <supported_stat_operator>`.
+        additional keyword arguments, e.g., ``[{'operator': 'percentile',
+        'percent': 20}]``. All supported options are are given in
+        :ref:`this table <supported_stat_operator>`.
     output_products: dict
         For internal use only. A dict with statistics names as keys and
         preprocessorfiles as values. If products are passed as input, the