docs: Uploading updated diagram

[franciscojavierarceo]

What this PR does / why we need it:

• Updating the design documentation (NOT DONE)
• Adding the diagram that @tenzen-y and others contributed to (screen shot below)
  

Which issue(s) this PR fixes (optional, in Fixes #<issue number>, #<issue number>, ... format, will close the issue(s) when PR gets merged):
Fixes #

Checklist:

• Docs included if any changes are user facing

[google-oss-prow]

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[coveralls]

Pull Request Test Coverage Report for Build 9019481892

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.02%) to 35.431%

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Totals
Change from base Build 8997849275:	0.02%
Covered Lines:	4380
Relevant Lines:	12362

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💛 - Coveralls