docs: add resource policy to spec docs

[praneetap]

Issue #, if available:
Adding resource policy to docs
Description of changes:

Description of how you validated changes:
doc change
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 #1103 into develop will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           develop    #1103   +/-   ##
========================================
  Coverage    94.75%   94.75%           
========================================
  Files           71       71           
  Lines         3472     3472           
  Branches       678      678           
========================================
  Hits          3290     3290           
  Misses          93       93           
  Partials        89       89

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