doc: show direction is optional in FETCH/MOVE's FROM/IN syntax

It used to show direction was required for FROM/IN.
Reported-by: Rob <rirans@comcast.net>

Discussion: https://postgr.es/m/20211015165248.isqjceyilelhnu3k@localhost

Author: Rob <rirans@comcast.net>

Backpatch-through: 10

doc/src/sgml/ref/fetch.sgml

@@ -27,9 +27,10 @@ PostgreSQL documentation
  <refsynopsisdiv>
 <!-- Note the "direction" bit is also in ref/move.sgml -->
 <synopsis>
-FETCH [ <replaceable class="parameter">direction</replaceable> [ FROM | IN ] ] <replaceable class="parameter">cursor_name</replaceable>
+FETCH [ <replaceable class="parameter">direction</replaceable> ] [ FROM | IN ] <replaceable class="parameter">cursor_name</replaceable>
 
-<phrase>where <replaceable class="parameter">direction</replaceable> can be empty or one of:</phrase>
+<phrase>where <replaceable class="parameter">direction</replaceable> can
+be one of:</phrase>
 
     NEXT
     PRIOR

doc/src/sgml/ref/move.sgml

@@ -27,9 +27,10 @@ PostgreSQL documentation
  <refsynopsisdiv>
 <!-- Note the "direction" bit is also in ref/fetch.sgml -->
 <synopsis>
-MOVE [ <replaceable class="parameter">direction</replaceable> [ FROM | IN ] ] <replaceable class="parameter">cursor_name</replaceable>
+MOVE [ <replaceable class="parameter">direction</replaceable> ] [ FROM | IN ] <replaceable class="parameter">cursor_name</replaceable>
 
-<phrase>where <replaceable class="parameter">direction</replaceable> can be empty or one of:</phrase>
+<phrase>where <replaceable class="parameter">direction</replaceable> can
+be one of:</phrase>
 
     NEXT
     PRIOR