docs: namespaces concepts page #3724

Job	Run time
build (1.21.x, amd64, linux, ./pkg/amino/cmd/aminoscan)	15s
build (1.21.x, amd64, linux, ./pkg/amino/cmd/goscan)	14s
build (1.21.x, amd64, linux, ./pkg/autofile/cmd)	20s
build (1.21.x, amd64, linux, ./pkg/iavl/cmd/iaviewer)	21s
build (1.22.x, amd64, linux, ./pkg/amino/cmd/aminoscan)	14s
build (1.22.x, amd64, linux, ./pkg/amino/cmd/goscan)	8s
build (1.22.x, amd64, linux, ./pkg/autofile/cmd)	14s
build (1.22.x, amd64, linux, ./pkg/iavl/cmd/iaviewer)	14s
test (1.21.x, _test.flappy)	36s
test (1.21.x, _test.pkg.amino)	1m 37s
test (1.21.x, _test.pkg.bft)	2m 40s
test (1.21.x, _test.pkg.others)	1m 38s
test (1.22.x, _test.flappy)	31s
test (1.22.x, _test.pkg.amino)	1m 35s
test (1.22.x, _test.pkg.bft)	2m 39s
test (1.22.x, _test.pkg.others)	1m 27s
upload-coverage	10s
	14m 53s

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