Improve `lerp()`, `lerp_angle()` and `inverse_lerp()` documentation
Improve `lerp()`, `lerp_angle()` and `inverse_lerp()` documentation

This clarifies that `lerp()` can be used both for interpolation
and extrapolation.

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