Modified preload guide to change objects to consistent ones

[cometcake575]

The current preload examples (Hornet Sentinel and the Cliffs_01 Cornifer Card) aren't great, and can cause some confusion about whether preloading is actually working as they sometimes don't appear to spawn.

Hornet Sentinel, like most bosses, doesn't work properly outside her normal circumstances, so won't function as expected.

The Cliffs_01 Cornifer Card will only spawn once Cornifer has left Howling Cliffs, meaning on other save files it will not appear.

The Primal Aspid and King's Pass Platform objects appear to work as expected at any point without requiring changes, making them better examples to use here.

(They can be substituded with anything else that works under any circumstances, they're just two examples I know of)

[cometcake575]

Might also be good to mention that people may want to rename their instantiated enemies because names are tied to the PersistentBoolItems that control whether they stay dead (and by default all instantiated copies will have the same name, that being the prefab name followed by (Clone)), but not sure if that'd be relevant to the preloads page