[DOCS] remove shmmax example in Linux section

The following documentation comment has been logged on the website:

Page: https://www.postgresql.org/docs/9.5/static/kernel-resources.html
Description:

Hi,

I'm refer to this document:
https://www.postgresql.org/docs/9.5/static/kernel-resources.html

In "Linux" section, show an example of setting shmmax to 16GB, when this
change is not needed from pg 9.3.

Maybe just remove to avoid confusion?
Maybe also shmall also not needed ?


Regards,
Gorka