doc: add missing documentation for paramEncoding

This option has existed ever since generateKeyPair was added in 2019 or
so, but I apparently forgot to document it.

PR-URL: nodejs#45523
Reviewed-By: Yagiz Nizipli <yagiz@nizipli.com>
Reviewed-By: Filip Skokan <panva.ip@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

doc/api/crypto.md

@@ -3739,6 +3739,8 @@ changes:
   * `generator`: {number} Custom generator (DH). **Default:** `2`.
   * `groupName`: {string} Diffie-Hellman group name (DH). See
     [`crypto.getDiffieHellman()`][].
+  * `paramEncoding`: {string} Must be `'named'` or `'explicit'` (EC).
+    **Default:** `'named'`.
   * `publicKeyEncoding`: {Object} See [`keyObject.export()`][].
   * `privateKeyEncoding`: {Object} See [`keyObject.export()`][].
 * `callback`: {Function}
@@ -3851,6 +3853,8 @@ changes:
   * `generator`: {number} Custom generator (DH). **Default:** `2`.
   * `groupName`: {string} Diffie-Hellman group name (DH). See
     [`crypto.getDiffieHellman()`][].
+  * `paramEncoding`: {string} Must be `'named'` or `'explicit'` (EC).
+    **Default:** `'named'`.
   * `publicKeyEncoding`: {Object} See [`keyObject.export()`][].
   * `privateKeyEncoding`: {Object} See [`keyObject.export()`][].
 * Returns: {Object}