docs: fix Docker instructions

[ThirdEyeSqueegee]

Issue #, if available:
N/A

Description of changes:
Improve Docker instructions

• Fix agent binary name
• Add client application Dockerfile example
• Fix example YAML indentation
• Improve auth setup instructions

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.88%. Comparing base (8554c56) to head (e4bb9ae).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #154   +/-   ##
=======================================
  Coverage   91.88%   91.88%           
=======================================
  Files          14       14           
  Lines        2404     2404           
  Branches     2404     2404           
=======================================
  Hits         2209     2209           
  Misses        147      147           
  Partials       48       48           

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