Copy-edit the docs changes of OWNER TO CURRENT/SESSION_USER additions.

Commit 31eae602 added new syntax to many DDL commands to use CURRENT_USER
or SESSION_USER instead of role name in ALTER ... OWNER TO, but because
of a misplaced '{', the syntax in the docs implied that the syntax was
"ALTER ... CURRENT_USER", instead of "ALTER ... OWNER TO CURRENT_USER".
Fix that, and also the funny indentation in some of the modified syntax
blurps.

doc/src/sgml/ref/alter_large_object.sgml

@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-ALTER LARGE OBJECT <replaceable class="PARAMETER">large_object_oid</replaceable> { OWNER TO <replaceable>new_owner</replaceable> | CURRENT_USER | SESSION_USER }
+ALTER LARGE OBJECT <replaceable class="PARAMETER">large_object_oid</replaceable> OWNER TO { <replaceable>new_owner</replaceable> | CURRENT_USER | SESSION_USER }
 </synopsis>
  </refsynopsisdiv>
 

doc/src/sgml/ref/alter_opclass.sgml

@@ -25,7 +25,7 @@ ALTER OPERATOR CLASS <replaceable>name</replaceable> USING <replaceable class="p
     RENAME TO <replaceable>new_name</replaceable>
 
 ALTER OPERATOR CLASS <replaceable>name</replaceable> USING <replaceable class="parameter">index_method</replaceable>
-          { OWNER TO <replaceable>new_owner</replaceable> | CURRENT_USER | SESSION_USER }
+    OWNER TO { <replaceable>new_owner</replaceable> | CURRENT_USER | SESSION_USER }
 
 ALTER OPERATOR CLASS <replaceable>name</replaceable> USING <replaceable class="parameter">index_method</replaceable>
     SET SCHEMA <replaceable>new_schema</replaceable>

doc/src/sgml/ref/alter_operator.sgml

@@ -22,7 +22,7 @@ PostgreSQL documentation
  <refsynopsisdiv>
 <synopsis>
 ALTER OPERATOR <replaceable>name</replaceable> ( { <replaceable>left_type</replaceable> | NONE } , { <replaceable>right_type</replaceable> | NONE } )
-             { OWNER TO <replaceable>new_owner</replaceable> | CURRENT_USER | SESSION_USER }
+    OWNER TO { <replaceable>new_owner</replaceable> | CURRENT_USER | SESSION_USER }
 
 ALTER OPERATOR <replaceable>name</replaceable> ( { <replaceable>left_type</replaceable> | NONE } , { <replaceable>right_type</replaceable> | NONE } )
     SET SCHEMA <replaceable>new_schema</replaceable>