pgsql: Use in pg_upgrade's procedure

Use <substeps> in pg_upgrade's procedure

For clarity, so that the substeps are not numbered identically to the
outer procedure's steps.

Per report from Andy Colson in
http://www.postgresql.org/message-id/55D789B5.7040308@squeakycode.net

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/9646d2fd62a444ab4502e49dfe3cbf9d7350c5e2

Modified Files
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doc/src/sgml/ref/pgupgrade.sgml |    4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)