Re: clean up docs for log_statement_sample_rate

[Christoph Berg]

Re: Justin Pryzby 2019-03-28 <20190328135918.ga27...@telsasoft.com>
> +         Determines the fraction of statements that exceed
> +         <xref linkend="guc-log-min-duration-statement"/> to be logged.
> +         The default is <literal>1</literal>, meaning log all such
                                    ^ 1.0

Thanks for taking care of this!
Christoph