Rename jarowinkler to jaro_winkler.

As per: elastic/elasticsearch#27526

Author: codebrain

src/Nest/Search/Suggesters/TermSuggester/StringDistance.cs

@@ -18,7 +18,7 @@ public enum StringDistance
 		DamerauLevenshtein,
 		[EnumMember(Value = "levenstein")]
 		Levenstein,
-		[EnumMember(Value = "jarowinkler")]
+		[EnumMember(Value = "jaro_winkler")]
 		Jarowinkler,
 		[EnumMember(Value = "ngram")]
 		Ngram