[DOCS] Missing Adjective that's rather important

The following documentation comment has been logged on the website:

Page: https://www.postgresql.org/docs/9.6/static/ddl-partitioning.html
Description:

Hello,

I had somehow overlooked "partitioning" as a "feature" of Postgres, since
Postgres has always been capable of implementing partitions. But I stumbled
across this page while reviewing the latest feature list:

https://www.postgresql.org/docs/current/static/ddl-partitioning.html

The author apparently thinks there's only one kind of table partitioning,
but there are two, commonly known as "horizontal" and "vertical". Horizontal
partitioning is what's discussed on that page and divides a table by the
value of some attribute (column) or collection of attributes. Vertical
partitioning, in contrast, divides up columns into different tables thus
requiring joins to "reconstitute the table", also, of course, based upon
some attribute or collection of attributes.

Overall, it's a reasonable articulation, more of a how-to and
what-to-watch-out-for than a genuine discrete feature - presuming I read the
page correctly! However, if you're well aware of the distinction between
horizontal and vertical partitioning, the document reads rather awkwardly.

This can easily be resolved by the inclusion of the adjective "horizontal"
in front of "partitioning" in various places, especially in the first few
instances. 

I might point out that the whole page should be reviewed and some sections
re-written in light of the fact that Postgres has always supported both
horizontal and vertical partitioning through the traditional means, it's
just Postgres has features to help ease the implementation required to pull
it off, though that page only discusses horizontal partitioning, if I read
it correctly.

Vertical partitioning, of course, already has a lot of help through more
traditional means such as views. Perhaps a small line or three mentioning
vertical partitioning would be helpful for clarity.

I'd be happy to take a stab at it if anyone wants, but it will have to wait
for May!

Regards,
Richard