docs: encode/decode transaction

[ryanchristo]

Description

Closes: #10102

Adds examples for encoding/decoding a transaction using the CLI. Also fixes CLI use and description.

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Author Checklist

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• included the correct docs: prefix in the PR title
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• confirmed the correct docs: prefix in the PR title
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[codecov]

Codecov Report

Merging #10133 (d7d4603) into master (6fc79b1) will increase coverage by 0.00%.
The diff coverage is 100.00%.

❗ Current head d7d4603 differs from pull request most recent head 9fad221. Consider uploading reports for the commit 9fad221 to get more accurate results

@@           Coverage Diff           @@
##           master   #10133   +/-   ##
=======================================
  Coverage   63.62%   63.63%           
=======================================
  Files         573      573           
  Lines       53606    53606           
=======================================
+ Hits        34109    34110    +1     
+ Misses      17550    17549    -1     
  Partials     1947     1947           

Impacted Files	Coverage Δ
x/auth/client/cli/decode.go	60.00% <100.00%> (ø)
x/auth/client/cli/encode.go	76.00% <100.00%> (ø)
crypto/keys/internal/ecdsa/privkey.go	84.21% <0.00%> (+1.75%)	⬆️

[orijbot]

Visit https://dashboard.github.orijtech.com?back=0&pr=10133&remote=false&repo=cosmos%2Fcosmos-sdk to see benchmark details.

[amaury1093]

lgtm!