chore: regenerate README

[yoshi-automation]

This PR was generated using Autosynth. 🌈

Log from Synthtool

2021-01-15 19:44:49,314 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-datastore/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2021-01-15 19:44:50,224 synthtool [DEBUG] > Wrote metadata to .github/readme/synth.metadata/synth.metadata.

Full log will be available here:
https://source.cloud.google.com/results/invocations/82039860-7757-46b1-ba3f-aaeddfe1ba4b/targets

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[yoshi-approver]

Rubber stamped PR!

[codecov]

Codecov Report

Merging #311 (c0c74d0) into master (59e0110) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master     #311   +/-   ##
=========================================
  Coverage     56.74%   56.74%           
  Complexity      384      384           
=========================================
  Files            48       48           
  Lines          2395     2395           
  Branches        265      265           
=========================================
  Hits           1359     1359           
  Misses          929      929           
  Partials        107      107           

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