Minor adjustment to pg_aios output naming

Hi,

I've noticed a minor inconsistency in the output of pg_aios.

According to the documentation, the values for 'operation' are described 
as:

   <literal>readv</literal>, a vectored read
   ...
   <literal>writev</literal>, a vectored write

However, in actual output, they appear as read and write -- without the 
trailing v:

   =# select operation from pg_aios;
   ..
   operation       | read

While this discrepancy is unlikely to cause any real issues, it would be 
better to keep the naming consistent.

I was a bit unsure which form to align to.
There are currently no other types of read/write operations in pg_aios, 
so the shorter form might have been sufficient.
However, using the 'v'-suffixed names makes the vectored nature of these 
operations explicit and future-proofs
the naming in case other variants are introduced later.


What do you think?

Best regards,

-- 
Regards,

--
Atsushi Torikoshi
Seconded from NTT DATA GROUP CORPORATION to SRA OSS K.K.