Replace issuer to admin in docs

[masihyeganeh]

Description

Reviewers checklist:

• Try to write more meaningful comments with clear actions to be taken.
• Nit-picking should be unblocking. Focus on core issues.

Authors checklist

• Provide a concise and meaningful description
• Review the code yourself first, before making the PR.
• Annotate your PR in places that require explanation.
• Think and try to split the PR to smaller PR if it is big.

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This change is 

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 36.09%. Comparing base (bfafcc1) to head (a0d9614).

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #819   +/-   ##
=======================================
  Coverage   36.09%   36.09%           
=======================================
  Files         180      180           
  Lines       50627    50627           
=======================================
  Hits        18276    18276           
  Misses      28902    28902           
  Partials     3449     3449           

Flag	Coverage Δ
coreum	31.74% <ø> (ø)
coreum-integration-tests-modules	22.57% <ø> (+0.02%)	⬆️

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[miladz68]

Reviewed 7 of 7 files at r1, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @dzmitryhil, @wojtek-coreum, and @ysv)

[miladz68]

Reviewed 1 of 1 files at r2, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @dzmitryhil, @wojtek-coreum, and @ysv)

[dzmitryhil]

Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @wojtek-coreum and @ysv)

[masihyeganeh]

Reviewed 5 of 7 files at r1, 1 of 1 files at r2, 1 of 1 files at r3, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @wojtek-coreum and @ysv)