fix mis-spelling in fuzz.go
@@ -32,7 +32,7 @@ import "github.com/prometheus/prometheus/pkg/textparse"
//
// Further input samples should go in the folders fuzz-data/ParseMetric/corpus.
//
-// Repeat for ParseMetricSeletion, ParseExpr and ParseStmt.
+// Repeat for ParseMetricSelection, ParseExpr and ParseStmt.
// Tuning which value is returned from Fuzz*-functions has a strong influence
// on how quick the fuzzer converges on "interesting" cases. At least try
