-Fixed code documentation of API Auth Key format

[allanchua101]

Issue #, if available:

Description of changes: I updated the broken section of the documentation which confuses ApiKey users.

Description of how you validated changes:

Checklist:

• Write/update tests
• make pr passes
• Update documentation
• Verify transformed template deploys and application functions as expected
• Add/update example to examples/2016-10-31

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

[codecov-io]

Codecov Report

Merging #1359 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1359   +/-   ##
=======================================
  Coverage   94.67%   94.67%           
=======================================
  Files          77       77           
  Lines        4130     4130           
  Branches      815      815           
=======================================
  Hits         3910     3910           
  Misses        108      108           
  Partials      112      112

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