improve doc (set encoding=utf-8)

README.md

@@ -229,6 +229,7 @@ let g:lightline = {
 If the triangles do not appear (but you get some spaces or weird characters like <bf> or ¿), firstly try adding
 ```vim
 scriptencoding utf-8
+set encoding=utf-8
 ```
 to the head of your `.vimrc`.
 Still you have weird characters, use the unicode numbers. For powerline font

doc/lightline.txt

@@ -934,6 +934,7 @@ Problem 8:					*lightline-problem-8*
 		weird characters like <bf> or ¿), firstly try adding
 >
 			scriptencoding utf-8
+			set encoding=utf-8
 <
 		to the head of your .vimrc(_vimrc). Still you have weird
 		characters, use the unicode numbers. For |powerline| font