pgsql: Now that the diskchecker.pl author has updated the download link

Now that the diskchecker.pl author has updated the download link on his
website, revert the separate link to the download git repository.

Backpatch from 9.0 to current.

Branch
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REL9_2_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/99dd2a390f8b0129092fe62a303b0cd1df547691

Modified Files
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doc/src/sgml/wal.sgml | 6 ++----
1 files changed, 2 insertions(+), 4 deletions(-)