Add README for k8s multi cluster plugin

[ffjlabo]

What this PR does:

as title

Why we need it:

I want to describe how to run k8s multicluster plugin locally.

Which issue(s) this PR fixes:

Part of #5006

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]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 27.79%. Comparing base (c3d15b3) to head (c012e03).
Report is 3 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5854      +/-   ##
==========================================
- Coverage   27.80%   27.79%   -0.02%     
==========================================
  Files         510      510              
  Lines       54301    54329      +28     
==========================================
  Hits        15101    15101              
- Misses      38054    38082      +28     
  Partials     1146     1146              

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[t-kikuc]

TODO: Let's add links to each plugin README in somewhere (like root README? pipedv1 README? or another) because this file is hard to find.

[t-kikuc]

we need to specify the oldest version which is compatible with pipedv1 or just specify latest

[ffjlabo]

add comment on b29e4bf.

[t-kikuc]

@ffjlabo
Precisely, v0.51.3 does not contain some commits of plugins since they're not cherry picked.

[t-kikuc]

We need to specify the commit when we released v0.51.3 instead of release-v0.51.x branch

[ffjlabo]

@t-kikuc

Precisely, v0.51.3 does not contain some commits of plugins since they're not cherry picked.

We need to specify the commit when we released v0.51.3 instead of release-v0.51.x branch

Thank you.
So, how about describing it using the upstream of the master branch?
The whole fixes for plugins are stored in that branch, and this is the docs for running locally with make command.

[t-kikuc]

@ffjlabo
I agree!

[ffjlabo]

fixed on c012e03

[t-kikuc]

Mention 'Currently only QuickSync is supported' somewhere

[ffjlabo]

fixed on dab25fd

[t-kikuc]

I think the examples should be moved to https://github.com/pipe-cd/examples in the future.

What about for now? Put in examples/ or the examples repo?
WDYT? @Warashi @khanhtc1202

[ffjlabo]

I think the examples should be moved to https://github.com/pipe-cd/examples in the future.

I agree with it. I think the examples for built-in plugins should be located in it.

What about for now? Put in examples/ or the examples repo?

I think we should put them in examples for now.
Currently, some errors will occur when there are app.pipecd.yaml files for both pipedv0 and pipedv1.

[t-kikuc]

I think we should put them in examples for now.

I agree! It's still like a draft.

I approve, and if others have a different opinion, I'll reconsider it.

[Warashi]

I agree with putting them under the plugin implementation directory for now because the configuration format may change in the future, as written in the head of this README. Putting them here is better because we can reduce the change scope in future pull requests; they are both under the plugin implementation directory.

[t-kikuc]

Thank you!!!
Let's try!!!!!!!

[Warashi]

LGTM 👍🏻