docs: Update to specify AppStream image should be started in main account not member account

[nguyen102]

Issue #, if available:

Description of changes:
docs: Update to specify AppStream image should be started in main account not member account

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AS review ticket id:

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

[codecov]

Codecov Report

Merging #770 (a0d03ab) into develop (e3c6c22) will not change coverage.
The diff coverage is n/a.

❗ Current head a0d03ab differs from pull request most recent head 3176fc1. Consider uploading reports for the commit 3176fc1 to get more accurate results

@@           Coverage Diff            @@
##           develop     #770   +/-   ##
========================================
  Coverage    52.10%   52.10%           
========================================
  Files          272      272           
  Lines        14522    14522           
  Branches      2286     2285    -1     
========================================
  Hits          7566     7566           
  Misses        6106     6106           
  Partials       850      850           

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