Add piped plugin SDK release docs

[khanhtc1202]

What this PR does:

ssia

Why we need it:

We want to note the release process for piped-plugin-sdk-go.

Which issue(s) this PR fixes:

Part of #5259
Part of #5530

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 28.76%. Comparing base (8c1876c) to head (872da89).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6210      +/-   ##
==========================================
- Coverage   28.77%   28.76%   -0.02%     
==========================================
  Files         559      559              
  Lines       59523    59523              
==========================================
- Hits        17127    17119       -8     
- Misses      41081    41090       +9     
+ Partials     1315     1314       -1     

Flag	Coverage Δ
.	23.22% <ø> (-0.03%)	⬇️
.-pkg-app-pipedv1-plugin-analysis	32.64% <ø> (ø)
.-pkg-app-pipedv1-plugin-kubernetes	60.24% <ø> (ø)
.-pkg-app-pipedv1-plugin-kubernetes_multicluster	67.48% <ø> (ø)
.-pkg-app-pipedv1-plugin-scriptrun	54.83% <ø> (ø)
.-pkg-app-pipedv1-plugin-terraform	39.49% <ø> (ø)
.-pkg-app-pipedv1-plugin-wait	35.51% <ø> (ø)
.-pkg-app-pipedv1-plugin-waitapproval	55.73% <ø> (ø)
.-pkg-plugin-sdk	50.37% <ø> (+0.19%)	⬆️
.-tool-actions-gh-release	19.23% <ø> (ø)
.-tool-actions-plan-preview	25.51% <ø> (ø)
.-tool-codegen-protoc-gen-auth	0.00% <ø> (ø)

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[ffjlabo]

@khanhtc1202
How about merging this docs to the RELEASES.md in #6209

[khanhtc1202]

@ffjlabo I don't have strong objection, let me change as your suggestion 👌