Add TlsVersion documentation.

Author: bgrainger

docs/content/connection-options.md

@@ -133,6 +133,11 @@ These are the options that need to be used in order to configure a connection to
     <td></td>
     <td>Specifies which certificate should be used from the Certificate Store specified in the setting above. This option must be used to indicate which certificate in the store should be used for authentication.</td>
   </tr>
+  <tr>
+    <td>Tls Version, TlsVersion, Tls-Version</td>
+    <td></td>
+    <td>Specifies which TLS versions may be used during TLS negotiation. The default value of <code>null</code> allows the OS to determine the TLS version to use (see <a href="https://docs.microsoft.com/en-us/dotnet/framework/network-programming/tls" title="Transport Layer Security (TLS) best practices with the .NET Framework">documentation</a>); this is the recommended setting. Otherwise, to restrict the versions that can be used, specify a comma-delimited list of versions taken from the following: <code>TLS 1.0</code>, <code>TLS 1.1.</code>, <code>TLS 1.2</code>, <code>TLS 1.3</code>. (This option allows each version to be specified in a few different formats: <code>Tls12</code>, <code> Tlsv1.2</code>, <code>TLS 1.2</code>, <code>Tls v1.2</code>; they are treated equivalently.)</td>
+  </tr>
 </table>
 
 Connection Pooling Options