API function to update existing bot created issue with new comments

[lubegasimon]

@epicallan

• we search for all issues by term bot and sort them by comments
• then we call addIssuesToRepo function that takes in the returned results from the search

[epicallan]

• assume you only have new issues to add to an existing issue.

interface Issue {
  title: string;
  body: string;
}

type Issues = issue[]

• So if our new comments are for a TODO issue we need to add our new comments (body) to our existing TODO issue as a new comment.

• Remember each issue has a predictable issue title, hence we can update particular issues basing on that. https://github.com/Akilihub/github-todos/blob/master/src/lib/github/issue-presenter.ts#L23

So we need an API function that adds a comment (body) to an existing issue.