docs: Add DataFrame.applymap documentation (#326)

* docs: Add `DataFrame.applymap` documentation

* fix rendering in the remote function requirements section

Author: shobsi

README.rst

@@ -304,7 +304,7 @@ following IAM roles:
 * BigQuery Connection Admin (roles/bigquery.connectionAdmin)
 * Cloud Functions Developer (roles/cloudfunctions.developer)
 * Service Account User (roles/iam.serviceAccountUser) on the
-  `service account <https://cloud.google.com/functions/docs/reference/iam/roles#additional-configuration> `
+  `service account <https://cloud.google.com/functions/docs/reference/iam/roles#additional-configuration>`__
   ``[email protected]``
 * Storage Object Viewer (roles/storage.objectViewer)
 * Project IAM Admin (roles/resourcemanager.projectIamAdmin)

third_party/bigframes_vendored/pandas/core/frame.py

@@ -2961,7 +2961,6 @@ def map(self, func, na_action: Optional[str] = None) -> DataFrame:
         to every element of a DataFrame.
 
         .. note::
-
            In pandas 2.1.0, DataFrame.applymap is deprecated and renamed to
            DataFrame.map.
 
@@ -3038,6 +3037,8 @@ def map(self, func, na_action: Optional[str] = None) -> DataFrame:
         """
         raise NotImplementedError(constants.ABSTRACT_METHOD_ERROR_MESSAGE)
 
+    applymap = map
+
     # ----------------------------------------------------------------------
     # Merging / joining methods