Add warning when choosing the PocketChange option that it will decrease privacy

[johnr365]

Currently the PocketChange option does not give users a prior warning of any privacy implications.

Given that Monero offers privacy by default, and PocketChange decreases this, it should be highlighted.

The current text says:

"To reduce waiting time on repeated spending, Monerujo can create spare change at the expensive of higher fees. It'll try to create and maintain 10 coins of the selected amount."

Perhaps it could be adjusted to:

"To reduce waiting time on repeated spending, Monerujo can create spare change at the expensive of higher fees and reduced privacy (read more). It'll try to create and maintain 10 coins of the selected amount."

If it's possible to add a hyperlink, then read more could launch the default browser and take a user to a web page that explains more details.

[dnaleor]

This feature should be deactivated without at least these changes I proposed (not refilling pockets unless they are all used) here: #907

Relevant article on XWallet with similar issue here: https://weuse.cash/2018/01/18/software-implementation-matters/