Correct TryReadTo ref assembly parameter name (#39594)

Author: benaadams

src/libraries/System.Memory/ref/System.Memory.cs

@@ -283,7 +283,7 @@ public void Rewind(long count) { }
         public bool TryReadTo(out System.Buffers.ReadOnlySequence<T> sequence, System.ReadOnlySpan<T> delimiter, bool advancePastDelimiter = true) { throw null; }
         public bool TryReadTo(out System.Buffers.ReadOnlySequence<T> sequence, T delimiter, bool advancePastDelimiter = true) { throw null; }
         public bool TryReadTo(out System.Buffers.ReadOnlySequence<T> sequence, T delimiter, T delimiterEscape, bool advancePastDelimiter = true) { throw null; }
-        public bool TryReadTo(out System.ReadOnlySpan<T> sequence, System.ReadOnlySpan<T> delimiter, bool advancePastDelimiter = true) { throw null; }
+        public bool TryReadTo(out System.ReadOnlySpan<T> span, System.ReadOnlySpan<T> delimiter, bool advancePastDelimiter = true) { throw null; }
         public bool TryReadTo(out System.ReadOnlySpan<T> span, T delimiter, bool advancePastDelimiter = true) { throw null; }
         public bool TryReadTo(out System.ReadOnlySpan<T> span, T delimiter, T delimiterEscape, bool advancePastDelimiter = true) { throw null; }
         public bool TryReadToAny(out System.Buffers.ReadOnlySequence<T> sequence, System.ReadOnlySpan<T> delimiters, bool advancePastDelimiter = true) { throw null; }