doc: Clarify expected type of `Object *` parameters in Tree methods
doc: Clarify expected type of `Object *` parameters in Tree methods

They're meant to be `TreeItem *` but this can't be bound in Variant.

Fixes #20538.

BastiaanOlij/godot,ZuBsPaCe/godot,pkowal1982/godot,vkbsb/godot,Valentactive/godot,guilhermefelipecgs/godot,godotengine/godot,vnen/godot,sanikoyes/godot,sanikoyes/godot,guilhermefelipecgs/godot,josempans/godot,ZuBsPaCe/godot,BastiaanOlij/godot,BastiaanOlij/godot,vkbsb/godot,godotengine/godot,Valentactive/godot,godotengine/godot,Valentactive/godot,firefly2442/godot,godotengine/godot,pkowal1982/godot,Shockblast/godot,ZuBsPaCe/godot,akien-mga/godot,Zylann/godot,akien-mga/godot,akien-mga/godot,guilhermefelipecgs/godot,Faless/godot,Shockblast/godot,ZuBsPaCe/godot,Valentactive/godot,Faless/godot,vnen/godot,josempans/godot,pkowal1982/godot,josempans/godot,vnen/godot,Faless/godot,Zylann/godot,vkbsb/godot,josempans/godot,Zylann/godot,firefly2442/godot,Faless/godot,godotengine/godot,vkbsb/godot,vnen/godot,akien-mga/godot,guilhermefelipecgs/godot,akien-mga/godot,vkbsb/godot,josempans/godot,Faless/godot,pkowal1982/godot,josempans/godot,firefly2442/godot,BastiaanOlij/godot,vkbsb/godot,Valentactive/godot,sanikoyes/godot,akien-mga/godot,firefly2442/godot,sanikoyes/godot,guilhermefelipecgs/godot,vnen/godot,Zylann/godot,sanikoyes/godot,BastiaanOlij/godot,firefly2442/godot,sanikoyes/godot,Faless/godot,godotengine/godot,vnen/godot,Zylann/godot,ZuBsPaCe/godot,josempans/godot,Zylann/godot,guilhermefelipecgs/godot,akien-mga/godot,ZuBsPaCe/godot,vkbsb/godot,Shockblast/godot,BastiaanOlij/godot,pkowal1982/godot,guilhermefelipecgs/godot,pkowal1982/godot,pkowal1982/godot,Valentactive/godot,ZuBsPaCe/godot,vkbsb/godot,akien-mga/godot,Faless/godot,Shockblast/godot,Shockblast/godot,vnen/godot,Valentactive/godot,Valentactive/godot,godotengine/godot,firefly2442/godot,josempans/godot,guilhermefelipecgs/godot,firefly2442/godot,Zylann/godot,pkowal1982/godot,sanikoyes/godot,godotengine/godot,sanikoyes/godot,Faless/godot,BastiaanOlij/godot,Shockblast/godot,Shockblast/godot,Zylann/godot,BastiaanOlij/godot,firefly2442/godot,ZuBsPaCe/godot,vnen/godot,Shockblast/godot