Add docs for validation

[shuheiktgw]

SSIA

[github-actions]

Code Metrics Report

	main (f3c9c12)	#77 (33dc5e9)	+/-
Coverage	65.6%	65.6%	0.0%
Code to Test Ratio	1:0.4	1:0.4	0.0
Test Execution Time	3m21s	3m18s	-3s

Details

  |                     | main (f3c9c12) | #77 (33dc5e9) | +/-  |
  |---------------------|----------------|---------------|------|
  | Coverage            |          65.6% |         65.6% | 0.0% |
  |   Files             |             60 |            60 |    0 |
  |   Lines             |           8713 |          8713 |    0 |
  |   Covered           |           5713 |          5713 |    0 |
  | Code to Test Ratio  |          1:0.4 |         1:0.4 |  0.0 |
  |   Code              |          25491 |         25491 |    0 |
  |   Test              |          11137 |         11137 |    0 |
+ | Test Execution Time |          3m21s |         3m18s |  -3s |

Code coverage of files in pull request scope (24.2% → 24.2%)

Files	Coverage	+/-
grpc/federation/federation.pb.go	24.2%	0.0%

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Reported by octocov