Add description when creating a pr with "createOrUpdatePR"

[sogame]

When updating the PR, the description is set correctly:

danger-js/source/platforms/github/GitHubUtils.ts

Line 169 in cad36b6

body: config.body,

But it's missing when creating the PR.

[danger-public]

	Warnings
⚠️	These providers are missing from the README: bamboo

Generated by 🚫 dangerJS against 94688fe

[orta]

Looks good - thanks for the fix! I guess because I used it with peril it was always running multiple times

[sogame]

Hi @orta ,
So it actually works for you when running it multiple times?

If if do a new push (so the build triggers again), instead of updating the PR Danger fails with a GitHub error complaining that "Reference already exists":

Error:  RequestError [HttpError]: Reference already exists
    at /home/travis/build/sogame/danger-plugin-toolbox/node_modules/@octokit/request/dist-node/index.js:66:23
    at processTicksAndRejections (internal/process/task_queues.js:93:5) {
  name: 'HttpError',
  status: 422,
  headers: {
    'access-control-allow-origin': '*',
    'access-control-expose-headers': 'ETag, Link, Location, Retry-After, X-GitHub-OTP, X-RateLimit-Limit, X-RateLimit-Remaining, X-RateLimit-Reset, X-OAuth-Scopes, X-Accepted-OAuth-Scopes, X-Poll-Interval, X-GitHub-Media-Type, Deprecation, Sunset',
    connection: 'close',
    'content-length': '121',
    'content-security-policy': "default-src 'none'",
    'content-type': 'application/json; charset=utf-8',
    date: 'Sun, 12 Apr 2020 12:00:59 GMT',
    'referrer-policy': 'origin-when-cross-origin, strict-origin-when-cross-origin',
    server: 'GitHub.com',
    status: '422 Unprocessable Entity',
    'strict-transport-security': 'max-age=31536000; includeSubdomains; preload',
    vary: 'Accept-Encoding, Accept, X-Requested-With',
    'x-accepted-oauth-scopes': 'repo',
    'x-content-type-options': 'nosniff',
    'x-frame-options': 'deny',
    'x-github-media-type': 'github.v3; format=json',
    'x-oauth-scopes': 'repo',
    'x-ratelimit-limit': '5000',
    'x-ratelimit-remaining': '4895',
    'x-xss-protection': '1; mode=block'
  },
  request: {
    method: 'POST',
    url: 'https://api.github.com/repos/sogame/danger-plugin-toolbox/git/refs',
    headers: {
      accept: 'application/vnd.github.v3+json',
      'user-agent': 'octokit.js/16.43.1 Node.js/12.13.1 (Linux 4.15; x64)',
      authorization: 'token [REDACTED]',
      'content-type': 'application/json; charset=utf-8'
    },
    body: '{"ref":"refs/heads/test_danger_new","sha":"3ddbe2dcc7a303c1ddb4eba030dd00194d3249ac"}',
    request: { hook: [Function: bound bound register], validate: [Object] }
  },
  documentation_url: 'https://developer.github.com/v3/git/refs/#create-a-reference'
}
danger-results://tmp/danger-results.json

[peril-staging]

Thanks for the PR @sogame.

This PR has been shipped in v10.1.1 - CHANGELOG.