[docs] Sync docs to docs-v0.48.x/

[t-kikuc]

What this PR does / why we need it:

I synced docs-dev/ to docs-v0.48.x/ by make release/docs version=v0.48.x.

This includes changes about:

1. Patch released features

• feat: add support mention slack groups for NotificationReceiverSlack and NotificationMention #4903
• Ignore desiredCount of ECS when it's 0 or not set for AutoScaling #5030

2. Rearranging pages

• [docs] change the order of managing-piped, managing-controlplane #5119

Which issue(s) this PR fixes:

N/A

ffjlabo

[t-kikuc]

flaky test..

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 22.80%. Comparing base (08a777b) to head (e50fb6a).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5150      +/-   ##
==========================================
+ Coverage   22.78%   22.80%   +0.02%     
==========================================
  Files         412      412              
  Lines       43827    43827              
==========================================
+ Hits         9986     9996      +10     
+ Misses      33053    33044       -9     
+ Partials      788      787       -1     

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[ffjlabo]

Thank you!