Add magento/MAGENTO_ADMIN_PASSWORD to .credentials.example file

[danmooney2]

Add magento/MAGENTO_ADMIN_PASSWORD to .credentials.example file

Description

This is required to be filled out for tests to generate; however it is not present in the example file that gets copied over to the dev/tests/acceptance directory

Fixed Issues (if relevant)

1. magento/magento2-functional-testing-framework#: Issue title
2. ...

Contribution checklist

• [ ] Pull request has a meaningful description of its purpose
• [ ] All commits are accompanied by meaningful commit messages
• [ ] All new or changed code is covered with unit/verification tests (if applicable)
• [ ] All automated tests passed successfully (all builds are green)
• [ ] Changes to Framework doesn't have backward incompatible changes for tests or have related Pull Request with fixes to tests

[fredden]

This looks like a duplicate of https://github.com/magento/magento2-functional-testing-framework/pull/896.

[danmooney2]

https://github.com/magento/magento2-functional-testing-framework/pull/896