Automatic port of Rune.CompareTo EII (#4891)

Co-authored-by: carlossanlop <[email protected]>

Author: carlossanlop

xml/System.Text/Rune.xml

@@ -1694,10 +1694,20 @@ For more information, see <xref:System.Char.IsWhiteSpace%2A?displayProperty=name
         <Parameter Name="obj" Type="System.Object" Index="0" FrameworkAlternate="net-5.0" />
       </Parameters>
       <Docs>
-        <param name="obj">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
-        <remarks>To be added.</remarks>
+        <param name="other">The object to compare with the current instance.</param>
+        <summary>Compares the current instance to the specified object.</summary>
+        <returns>A signed integer indicating the position of this instance in the sort order in relation to <paramref name="other" />: <br />- Less than zero: This instance precedes <paramref name="other" />. 
+<br />- Zero: The instance has the same position in the sort order as <paramref name="other" />.
+<br />- Greater than zero: This instance follows <paramref name="other" />.</returns>
+        <remarks>
+          <format type="text/markdown"><![CDATA[
+
+## Remarks
+
+This member is an explicit interface member implementation. It can be used only when the <xref:System.Text.Rune> instance is cast to an <xref:System.IComparable> interface.
+
+          ]]></format>
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="ToLower">