add params to ScannerBuilder

python/pyarrow/_dataset.pyx

@@ -709,6 +709,14 @@ cdef class ScannerBuilder:
 
     It is used to pass information, notably a potential filter expression and a
     subset of columns to materialize.
+
+    Parameters
+    ----------
+    dataset : Dataset
+        The dataset to scan.
+    memory_pool : MemoryPool, default None
+        For memory allocations, if required. If not specified, uses the
+        default pool.
     """
 
     cdef:
@@ -767,7 +775,7 @@ cdef class ScannerBuilder:
 
         Returns
         -------
-        self : ScannerBuilder
+        Scanner
         """
         return Scanner.wrap(GetResultValue(self.builder.Finish()))
 
@@ -820,6 +828,8 @@ cdef class ScannerBuilder:
 cdef class Scanner:
     """A materialized scan operation with context and options bound.
 
+    Create this using the ScannerBuilder factory class.
+
     A scanner is the class that glues the scan tasks, data fragments and data
     sources together.
     """