[Enhancement]: Update Wii U guide to remove mentions of deleting NNIDs

[jonbarrow]

Checked Existing

• I have checked the repository for duplicate issues.

What enhancement would you like to see?

Update the notice at https://pretendo.network/docs/install/wiiu#pnid-setup to remove mentions of deleting NNIDs. We should instead encourage users to pick new names

Any other details to share? (OPTIONAL)

No response