Add XML doc comments for Get/SetRawSocketOption (#33390)

* Add XML doc comments for Get/SetRawSocketOption

I neglected to add XML doc comments for these new APIs in previous PR.  Fixing that.

* Update src/libraries/System.Net.Sockets/src/System/Net/Sockets/Socket.cs

Co-Authored-By: Günther Foidl <[email protected]>

Co-authored-by: Günther Foidl <[email protected]>

Author: stephentoub

src/libraries/System.Net.Sockets/src/System/Net/Sockets/Socket.cs

@@ -1818,6 +1818,17 @@ public void SetSocketOption(SocketOptionLevel optionLevel, SocketOptionName opti
             }
         }
 
+        /// <summary>Sets a socket option value using platform-specific level and name identifiers.</summary>
+        /// <param name="optionLevel">The platform-defined option level.</param>
+        /// <param name="optionName">The platform-defined option name.</param>
+        /// <param name="optionValue">The value to which the option should be set.</param>
+        /// <exception cref="ObjectDisposedException">The <see cref="Socket"/> has been closed.</exception>
+        /// <exception cref="SocketException">An error occurred when attempting to access the socket.</exception>
+        /// <remarks>
+        /// In general, the SetSocketOption method should be used whenever setting a <see cref="Socket"/> option.
+        /// The <see cref="SetRawSocketOption"/> should be used only when <see cref="SocketOptionLevel"/> and <see cref="SocketOptionName"/>
+        /// do not expose the required option.
+        /// </remarks>
         public void SetRawSocketOption(int optionLevel, int optionName, ReadOnlySpan<byte> optionValue)
         {
             ThrowIfDisposed();
@@ -1926,6 +1937,18 @@ public byte[] GetSocketOption(SocketOptionLevel optionLevel, SocketOptionName op
             return optionValue;
         }
 
+        /// <summary>Gets a socket option value using platform-specific level and name identifiers.</summary>
+        /// <param name="optionLevel">The platform-defined option level.</param>
+        /// <param name="optionName">The platform-defined option name.</param>
+        /// <param name="optionValue">The span into which the retrieved option value should be stored.</param>
+        /// <returns>The number of bytes written into <paramref name="optionValue"/> for a successfully retrieved value.</returns>
+        /// <exception cref="ObjectDisposedException">The <see cref="Socket"/> has been closed.</exception>
+        /// <exception cref="SocketException">An error occurred when attempting to access the socket.</exception>
+        /// <remarks>
+        /// In general, the GetSocketOption method should be used whenever getting a <see cref="Socket"/> option.
+        /// The <see cref="GetRawSocketOption"/> should be used only when <see cref="SocketOptionLevel"/> and <see cref="SocketOptionName"/>
+        /// do not expose the required option.
+        /// </remarks>
         public int GetRawSocketOption(int optionLevel, int optionName, Span<byte> optionValue)
         {
             ThrowIfDisposed();