README cleanup

[GriffinCodes]

The current readme has a bit of repetition, and some of the examples are completely wrong. For example:

// This method no longer exists, you have to authenticate
final GitHubClient github = GitHubClient.create(URI.create("https://api.github.com/"));
// IssueApi is now IssueClient
final IssueApi issueClient = github.createRepositoryClient("my-org", "my-repo").createIssueClient();
// listComments returns an Iterator, not a CompletableFuture
issueClient.listComments(ISSUE_ID).get().forEach(comment -> log.info(comment.body()));

Hopefully this makes the introduction to the project a bit smoother 🙂

Also, #63 was already fixed and can be closed

[barbatron]

ty 🙏