fix: add "either" option for param structure

fixes #190

partly addresses #226

Signed-off-by: Zachary Belford <belfordz66@gmail.com>

.gitignore

@@ -1,2 +1,3 @@
+.DS_Store
 build/
 node_modules/

spec.md

@@ -197,7 +197,7 @@ Field Name | Type | Description
 <a name="method-servers"></a>servers | [[Server Object](#server-object)] | An alternative `servers` array to service this method. If an alternative `servers` array is specified at the Root level, it will be overridden by this value.
 <a name="method-errors"></a>errors | [[Error Object](#error-object) \| [Reference Object](#reference-object)] | A list of custom application defined errors that MAY be returned. The Errors MUST have unique error codes.
 <a name="method-links"></a>links | [[Link Object](#link-object) \| [Reference Object](#reference-object)] | A list of possible links from this method call.
-<a name="method-param-structure"></a>paramStructure | `"by-name"` \| `"by-position"` | Format the server expects the params. Defaults to `"by-position"`.
+<a name="method-param-structure"></a>paramStructure | `"by-name"` \| `"by-position"` \| `"either"` | The expected format of the parameters. [As per the JSON-RPC 2.0 specification](https://www.jsonrpc.org/specification#parameter_structures), params may be either an array, an object, or either. Defaults to `"by-position"`.
 <a name="method-examples"></a>examples | [[Example Pairing Object](#example-pairing-object)] | Array of [Example Pairing Object](#example-pairing-object) where each example includes a valid params-to-result [Content Descriptor](#content-descriptor-object) pairing.
 
 This object MAY be extended with [Specification Extensions](#specification-extensions).