Update auth URL in DEPLOYING.md

[ghost]

Description

Update documentation to reflect accurate default auth URL configuration.

Resolves #465

Type of change

Please delete options that are not relevant.

• documentation update

How Has This Been Tested?

N/A

Test Configuration: N/A

• Toolchain: N/A
• SDK: N/A

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

[coveralls]

Coverage: 45.192%. Remained the same when pulling 6f2f56f on 465-auth-url into 251d249 on staging.