update shifu's messaging to "Kubernetes native IoT gateway"

[saiyan86]

What this PR does / why we need it:

Update shifu's messaging to "Kubernetes native IoT gateway"

Will this PR make the community happier?

Yes. This helps developers to understand Shifu's value proposition faster.

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

How is this PR tested

• unit test
• e2e test
• other (please specify)

Special notes for your reviewer:

Release note:

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (3418a57) 54.70% compared to head (0a03506) 54.78%.
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #803      +/-   ##
==========================================
+ Coverage   54.70%   54.78%   +0.08%     
==========================================
  Files          23       23              
  Lines        2287     2287              
==========================================
+ Hits         1251     1253       +2     
+ Misses        921      919       -2     
  Partials      115      115              

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