Fix spelling mistakes (#3300)

Author: grovesNL

xml/System.Text.Json/JsonSerializer.xml

@@ -591,7 +591,7 @@ The <xref:System.Text.Json.JsonWriterOptions> used to create the instance of the
         <param name="value">The value to convert.</param>
         <param name="options">Options to control serialization behavior.</param>
         <param name="cancellationToken">A token that may be used to cancel the write operation.</param>
-        <summary>Asynchronously converts a value of a type specified by a generic type parametaer to UTF-8 encoded JSON text and writes it to a stream.</summary>
+        <summary>Asynchronously converts a value of a type specified by a generic type parameter to UTF-8 encoded JSON text and writes it to a stream.</summary>
         <returns>A task that represents the asynchronous write operation.</returns>
         <remarks>To be added.</remarks>
       </Docs>
@@ -649,7 +649,7 @@ The <xref:System.Text.Json.JsonWriterOptions> used to create the instance of the
         <typeparam name="TValue">The type of the value.</typeparam>
         <param name="value">The value to convert.</param>
         <param name="options">Options to control the conversion behavior.</param>
-        <summary>Converts the value of a type specifed by a generic type parameter into a JSON string, encoded as UTF-8 bytes.</summary>
+        <summary>Converts the value of a type specified by a generic type parameter into a JSON string, encoded as UTF-8 bytes.</summary>
         <returns>A JSON string representation of the value, encoded as UTF-8 bytes.</returns>
         <remarks>To be added.</remarks>
       </Docs>