docs: clarify bgw_restart_time documentation

Author: Dave Cramer <davecramer@gmail.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/CADK3HHLZmqAQZ2ByPDQQ9yhGqax36kksq6sDkV0yYzsxw6ipvQ@mail.gmail.com

doc/src/sgml/bgworker.sgml

@@ -134,8 +134,8 @@ typedef struct BackgroundWorker
 
   <para>
    <structfield>bgw_restart_time</structfield> is the interval, in seconds, that
-   <command>postgres</command> should wait before restarting the process, in
-   case it crashes.  It can be any positive value,
+   <command>postgres</command> should wait before restarting the process in
+   the event that it crashes.  It can be any positive value,
    or <literal>BGW_NEVER_RESTART</literal>, indicating not to restart the
    process in case of a crash.
   </para>