fix: update readme for broadcastTransaction

[agraebe]

Fixes #1063

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[codecov]

Codecov Report

Merging #1064 (169b843) into master (61cbf80) will not change coverage.
The diff coverage is n/a.

❗ Current head 169b843 differs from pull request most recent head f9628b3. Consider uploading reports for the commit f9628b3 to get more accurate results

@@           Coverage Diff           @@
##           master    #1064   +/-   ##
=======================================
  Coverage   61.72%   61.72%           
=======================================
  Files         113      113           
  Lines        8194     8194           
  Branches     1503     1521   +18     
=======================================
  Hits         5058     5058           
  Misses       3006     3006           
  Partials      130      130           

Impacted Files	Coverage Δ
packages/cli/src/cli.ts	7.27% <0.00%> (ø)
packages/network/src/index.ts	59.45% <0.00%> (ø)

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[reedrosenbluth]

LGTM! left a minor comment