chore: regenerate README

[yoshi-automation]

This PR was generated using Autosynth. 🌈

Log from Synthtool

2021-04-19 21:06:18,340 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-appengine-admin/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2021-04-19 21:06:19,620 synthtool [DEBUG] > Wrote metadata to .github/readme/synth.metadata/synth.metadata.

Full log will be available here:
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[yoshi-approver]

Rubber stamped PR!

[codecov]

Codecov Report

Merging #25 (02f5a7a) into master (e6043d0) will decrease coverage by 0.22%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##             master      #25      +/-   ##
============================================
- Coverage     73.98%   73.76%   -0.23%     
  Complexity      365      365              
============================================
  Files            48       48              
  Lines          3156     3156              
  Branches         15       15              
============================================
- Hits           2335     2328       -7     
- Misses          806      813       +7     
  Partials         15       15              

Impacted Files	Coverage Δ	Complexity Δ
...pengine/v1/stub/AuthorizedDomainsStubSettings.java	75.78% <0.00%> (-1.06%)	11.00% <0.00%> (ø%)
...google/appengine/v1/stub/FirewallStubSettings.java	79.71% <0.00%> (-0.73%)	16.00% <0.00%> (ø%)
...ne/v1/stub/AuthorizedCertificatesStubSettings.java	76.05% <0.00%> (-0.71%)	15.00% <0.00%> (ø%)
...google/appengine/v1/stub/ServicesStubSettings.java	83.81% <0.00%> (-0.58%)	16.00% <0.00%> (ø%)
...oogle/appengine/v1/stub/InstancesStubSettings.java	83.81% <0.00%> (-0.58%)	16.00% <0.00%> (ø%)
...google/appengine/v1/stub/VersionsStubSettings.java	85.64% <0.00%> (-0.48%)	18.00% <0.00%> (ø%)
.../appengine/v1/stub/DomainMappingsStubSettings.java	84.79% <0.00%> (-0.47%)	18.00% <0.00%> (ø%)

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