doc: add doc about run on aws eks

[tokers]

Please answer these questions before submitting a pull request

• Why submit this pull request?

• Bugfix

• New feature provided

• Improve performance

• Backport patches

• Related issues

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Bugfix

• Description

• How to fix?

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New feature or improvement

• Describe the details and related test reports.

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Backport patches

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[tokers]

@membphis @moonming @gxthrj Please take a look when you have time.

[moonming]

great， we can post to apisix.apache.org too

[codecov-io]

Codecov Report

Merging #177 (b32a240) into master (958a02b) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #177   +/-   ##
=======================================
  Coverage   48.65%   48.65%           
=======================================
  Files          30       30           
  Lines        1482     1482           
=======================================
  Hits          721      721           
  Misses        675      675           
  Partials       86       86           

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