Remove duplicate i.e. from public API doc (#48169)

src/Compilers/Core/Portable/Symbols/IMethodSymbol.cs

@@ -132,7 +132,7 @@ public interface IMethodSymbol : ISymbol
         IMethodSymbol ConstructedFrom { get; }
 
         /// <summary>
-        /// Indicates whether the method is readonly, i.e.
+        /// Indicates whether the method is readonly,
         /// i.e. whether the 'this' receiver parameter is 'ref readonly'.
         /// Returns true for readonly instance methods and accessors
         /// and for reduced extension methods with a 'this in' parameter.