doc: adjust alignment of doc file list for "pg_waldump.sgml"

Backpatch-through: 10

Author: bmomjian

doc/src/sgml/ref/allfiles.sgml

@@ -215,7 +215,7 @@ Complete list of usable sgml source files in this directory.
 <!ENTITY pgtestfsync        SYSTEM "pgtestfsync.sgml">
 <!ENTITY pgtesttiming       SYSTEM "pgtesttiming.sgml">
 <!ENTITY pgupgrade          SYSTEM "pgupgrade.sgml">
-<!ENTITY pgwaldump         SYSTEM "pg_waldump.sgml">
+<!ENTITY pgwaldump          SYSTEM "pg_waldump.sgml">
 <!ENTITY postgres           SYSTEM "postgres-ref.sgml">
 <!ENTITY postmaster         SYSTEM "postmaster.sgml">
 <!ENTITY psqlRef            SYSTEM "psql-ref.sgml">