doc: Fix name of CRC algorithm in "Reliability" section.

This section claims we use CRC-32 for WAL records and two-phase
state files, but we've actually used CRC-32C since v9.5 (commit
5028f22f6e).  Fix that.

Reviewed-by: Robert Haas
Discussion: https://postgr.es/m/ZrUFpLP-w2zTAHqq%40nathan
Backpatch-through: 12

doc/src/sgml/wal.sgml

@@ -186,7 +186,7 @@
    <itemizedlist>
     <listitem>
      <para>
-      Each individual record in a WAL file is protected by a CRC-32 (32-bit) check
+      Each individual record in a WAL file is protected by a CRC-32C (32-bit) check
       that allows us to tell if record contents are correct. The CRC value
       is set when we write each WAL record and checked during crash recovery,
       archive recovery and replication.
@@ -212,7 +212,7 @@
     </listitem>
     <listitem>
      <para>
-      Individual state files in <filename>pg_twophase</filename> are protected by CRC-32.
+      Individual state files in <filename>pg_twophase</filename> are protected by CRC-32C.
      </para>
     </listitem>
     <listitem>