Docs: avoid confusing use of the word "synchronized"

It's misleading to call the data directory the "synchronized data
directory" when discussing a crash scenario when using pg_rewind's
--no-sync option.  Here we just remove the word "synchronized" to avoid
any possible confusion.

Author: Justin Pryzby
Discussion: https://postgr.es/m/20220411020336.GB26620@telsasoft.com
Backpatch-through: 12, where --no-sync was added

doc/src/sgml/ref/pg_rewind.sgml

@@ -210,8 +210,8 @@ PostgreSQL documentation
         to be written safely to disk.  This option causes
         <command>pg_rewind</command> to return without waiting, which is
         faster, but means that a subsequent operating system crash can leave
-        the synchronized data directory corrupt.  Generally, this option is
-        useful for testing but should not be used on a production
+        the data directory corrupt.  Generally, this option is useful for
+        testing but should not be used on a production
         installation.
        </para>
       </listitem>