Change readme.md readme with Atlassian Cloud auth instructions

[rafaelleonardocruz]

Working with Atlassian Cloud, We must replace password by an API token, it's not clear on readme.me.

I can submit a PR if you agree, but basically is something like:

Authentication

Are you using Atlassian Cloud? use your API token instead of your account password, you can generate one following these steps:

• access https://id.atlassian.com/manage-profile/security/api-tokens
• click on "Create API token" button and save it in a safe place (See more details about APIs auth on official page

Here's the official doc. https://developer.atlassian.com/cloud/jira/platform/basic-auth-for-rest-apis/

[pawelrychlik]

@rafaelleonardocruz the requested change makes a lot of sense, so yes please, your PR is welcome 🙏