pgsql: docs: Adapt wal_segment_size docs to fc49e24fa69.

docs: Adapt wal_segment_size docs to fc49e24fa69.

Before this change the docs weren't adapted to the fact that
wal_segment_size is now measured in bytes, rather than multiples of
wal_block_size.

Author: David Steele
Discussion: https://postgr.es/m/68ea97d6-2ed9-f339-e57d-ab3a33caf3b1@pgmasters.net
Backpatch: 11-, like fc49e24fa69 itself.

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/5fc1670bad9bfa138be1c790d529249e0706d38e

Modified Files
--------------
doc/src/sgml/config.sgml | 7 ++-----
1 file changed, 2 insertions(+), 5 deletions(-)