chore: regenerate README

[yoshi-automation]

This PR was generated using Autosynth. 🌈

Log from Synthtool

2020-11-04 01:40:18,447 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-bigquerydatatransfer/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working directory clean
2020-11-04 01:40:19,347 synthtool [DEBUG] > Wrote metadata to .github/readme/synth.metadata/synth.metadata.

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[yoshi-approver]

Rubber stamped PR!

[codecov]

Codecov Report

Merging #489 into master will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master     #489   +/-   ##
=========================================
  Coverage     74.68%   74.68%           
  Complexity      108      108           
=========================================
  Files             7        7           
  Lines           948      948           
  Branches         18       18           
=========================================
  Hits            708      708           
  Misses          220      220           
  Partials         20       20           

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