message: [cli] Fix api url for `vc env add`
  This PR fixes a POST request url to match the [api docs](https://vercel.com/docs/api#endpoints/secrets/create-a-new-secret) recommendation so that all data is in the body, not the query string.
diff: @@ -19,10 +19,9 @@ export default async function addEnvRecord(
  let values: string[] | undefined;
  if (envValue) {
  - const urlSecret = `/v2/now/secrets/${encodeURIComponent(envName)}`;
  const secrets = await Promise.all(
  targets.map(target =>
  - client.fetch<Secret>(urlSecret, {
  + client.fetch<Secret>('/v2/now/secrets', {
  method: 'POST',
  body: JSON.stringify({
  name: generateSecretName(envName, target),
  