[docs] Explain the builtin commands and the separating script for script run stage

[ffjlabo]

What this PR does / why we need it:

as title

Which issue(s) this PR fixes:

Fixes #

Does this PR introduce a user-facing change?:

• How are users affected by this change:
• Is this breaking change:
• How to migrate (if breaking change):

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 22.84%. Comparing base (58bf4ff) to head (48022da). Report is 50 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5127      +/-   ##
==========================================
+ Coverage   22.80%   22.84%   +0.04%     
==========================================
  Files         412      420       +8     
  Lines       43827    45247    +1420     
==========================================
+ Hits         9996    10338     +342     
- Misses      33044    34114    +1070     
- Partials      787      795       +8     

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[ffjlabo]

@t-kikuc Thank you for the comment 🙏 I fixed them.

• fix description for the usecase 3ab416e
  • clarified the options as isolated ones.
  • removed the one that is not recommended
• remove labels ed4f0b0
• wrong spell c502a27

[khanhtc1202]

@ffjlabo Could you check this 👀

[t-kikuc]

@khanhtc1202 Would you check again?