What this PR does / why we need it:
Reorders 2 sections and adds _index.md overview file for better locality(related concepts are closer) and content introduction: Extensions and Other components sections should be introduced earlier
Which issue(s) this PR fixes:
Fixes #
What this PR does / why we need it: Reorders 2 sections and adds
_index.md
overview file for better locality(related concepts are closer) and content introduction:Extensions
andOther components
sections should be introduced earlier Which issue(s) this PR fixes: Fixes #Special notes for your reviewer:
Release note: