Update xml/System.Text/StringBuilder.xml

Author: gewarren

xml/System.Text/StringBuilder.xml

@@ -5270,6 +5270,7 @@ The `Equals` method performs an ordinal comparison to determine whether the char
           <para>On .NET (Core), <see langword="true" /> if the characters in this instance and <paramref name="sb" /> are equal; otherwise, <see langword="false" />.</para>
           <para>On .NET Framework, <see langword="true" /> if this instance and <paramref name="sb" /> have equal string, <see cref="P:System.Text.StringBuilder.Capacity" />, and <see cref="P:System.Text.StringBuilder.MaxCapacity" /> values; otherwise, <see langword="false" />.</para>
         </returns>
+        <remarks>
           <format type="text/markdown"><![CDATA[
 
 ## Remarks