fix: apply CodeRabbit auto-fixes

Fixed 1 file(s) based on 1 unresolved review comment.

Co-authored-by: CodeRabbit <noreply@coderabbit.ai>

Author: coderabbitai[bot]

src/Elastic.Documentation.Configuration/Search/SearchConfiguration.cs

@@ -127,6 +127,8 @@ public static SearchConfiguration CreateSearchConfiguration(this ConfigurationFi
 		var synonyms = searchDto.Synonyms
 			.Where(s => s.Count > 1)
 			.Select(s => s.ToArray())
+			.GroupBy(s => s[0], StringComparer.OrdinalIgnoreCase)
+			.Select(g => g.First())
 			.ToArray();
 		var rules = searchDto.Rules.Select(ParseRule).ToImmutableArray();
 		var diminishTerms = searchDto.DiminishTerms.ToImmutableArray();
@@ -153,4 +155,4 @@ private static QueryRuleCriteria ParseCriteria(QueryRuleCriteriaDto dto) =>
 			Metadata = dto.Metadata,
 			Values = dto.Values.ToImmutableArray()
 		};
-}
+}