docs(api): deprecate to_array in favor of as_scalar in docstring (#10508)

## Description of changes

While reviewing the remaining table expression methods that needed
examples, I noticed that
[`to_array`](https://ibis-project.org/reference/expression-tables#ibis.expr.types.relations.Table.to_array)
did not include the deprecation docstring. The added deprecation note is
similar to that of
[`dropna`](https://ibis-project.org/reference/expression-tables#ibis.expr.types.relations.Table.dropna)
and
[`relabel`](https://ibis-project.org/reference/expression-tables#ibis.expr.types.relations.Table.relabel).

Author: IndexSeek

ibis/expr/types/relations.py

@@ -1812,13 +1812,8 @@ def difference(self, table: Table, *rest: Table, distinct: bool = True) -> Table
 
     @deprecated(as_of="9.0", instead="use table.as_scalar() instead")
     def to_array(self) -> ir.Column:
-        """View a single column table as an array.
+        """Deprecated - use `as_scalar` instead."""
 
-        Returns
-        -------
-        Value
-            A single column view of a table
-        """
         schema = self.schema()
         if len(schema) != 1:
             raise com.ExpressionError(