Clarify what a string being empty means
Clarify what a string being empty means

Should close https://github.com/godotengine/godot-docs/issues/2432

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