doc(README): add missing typo

Author: LouisMazel

README.md

@@ -319,7 +319,7 @@ multiline code
 
 (15) `acceptedFiles` can be used to set specifics file types allowed in chat. By default, all file types are allowed: `"*"`.
 
-Example: set `accepted-files="image/png, image/peg, application/pdf"` to allow `JPG` `PNG` and `PDF` files
+Example: set `"accepted-files="image/png, image/peg, application/pdf"` to allow `JPG` `PNG` and `PDF` files
 
 (16) `styles` can be used to customize your own theme. Ex: