Update Artsy RFCs Slack post

[dblandin]

Let's give the RFCs Slack post a refresh with this Slack Block Kit structure and the following GraphQL query:

fragment authorFields on Actor {
  login
  url
  avatarUrl
}

fragment issueCommentFields on IssueComment {
  createdAt
  author {
    login
  }
}

{
  search(query: "org:Artsy label:RFC state:open", type: ISSUE, first: 20) {
    issueCount
    edges {
      node {
        ... on Issue {
          participants {
            totalCount
          }
          timelineItems(last: 1, itemTypes: ISSUE_COMMENT) {
            nodes {
              ... on IssueComment {
                ...issueCommentFields
              }
            }
          }
          createdAt
          title
          url
          author {
            ...authorFields
          }
        }
        ... on PullRequest {
          participants {
            totalCount
          }
          timelineItems(last: 1, itemTypes: ISSUE_COMMENT) {
            nodes {
              ... on IssueComment {
                ...issueCommentFields
              }
            }
          }
          createdAt
          title
          url
          author {
            ...authorFields
          }
        }
      }
    }
  }
}

Current

Desired

[dblandin]

Closing with #31