pgsql: Doc: do a little copy-editing on Index Storage Parameters list.

Doc: do a little copy-editing on Index Storage Parameters list.

Add a paragraph break per suggestion from David G. Johnston.
Use a consistent voice for all the different parameter
descriptions, and fix a couple of grammatical issues.

Reported-by: Igor Korot <ikorot01(at)gmail(dot)com>
Co-authored-by: "David G. Johnston" <david(dot)g(dot)johnston(at)gmail(dot)com>
Co-authored-by: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Discussion: https://postgr.es/m/CA+FnnTz=EW1VQRpWB9J+G-NSchrPFcw4nR7d0JqzEK9jWKB35A@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/78637a8be20e49d8cbfdecf2d6db1f45b9695211

Modified Files
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doc/src/sgml/ref/create_index.sgml | 34 ++++++++++++++++++++--------------
1 file changed, 20 insertions(+), 14 deletions(-)