Ring size in documentation needs update to 16

[dimalinux]

The current documentation still says the ring size is 11: https://www.getmonero.org/resources/moneropedia/ring-size.html https://github.com/monero-project/monero-site/blob/master/_i18n/en/resources/moneropedia/ring-size.md

It should be updated to say that the ring size has been fixed at 16 since Fluorine Fermi.

[plowsof]

Duplicate #2032 closed with #2078