Update readme.md

readme.md

@@ -106,7 +106,7 @@ tone('aa+xa+a-ita-') // => aa3xa3a4ita4
 
 These are the main sounds. Everything else are variations of these
 sounds. These "variations" are accomplished in a structured way, see the
-[guide](https://tone.rest). Indic retroflex consonants are added with a
+[guide](https://tone.surf). Indic retroflex consonants are added with a
 dot on the tailless side. Arabic sounds are added with a dot on the
 tailed side usually. Clicks are mapped to the closest
 mouth-position-oriented sound. Ejectives and implosives are simply added