Update READMEs via plugin

[damondouglas]

Applied the following commands to update the repository's READMEs:

1. Installed the maven plugins:

mvn clean install -pl plugins/templates-maven-plugin -am

2. Ran the maven command to update/generate the repository's READMEs:

mvn clean prepare-package \
  -DskipTests \
  -PtemplatesSpec

See contributor-docs/code-contributions for more details.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 48.31%. Comparing base (b72eaa2) to head (4b12cbd).
Report is 5 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #1975      +/-   ##
============================================
+ Coverage     45.09%   48.31%   +3.22%     
+ Complexity     3935     1334    -2601     
============================================
  Files           835      410     -425     
  Lines         49703    22321   -27382     
  Branches       5232     2228    -3004     
============================================
- Hits          22412    10784   -11628     
+ Misses        25625    10866   -14759     
+ Partials       1666      671     -995     

Components	Coverage Δ
spanner-templates	67.29% <ø> (+1.01%)	⬆️
spanner-import-export	∅ <ø> (∅)
spanner-live-forward-migration	76.18% <ø> (ø)
spanner-live-reverse-replication	76.54% <ø> (ø)
spanner-bulk-migration	85.57% <ø> (ø)

see 444 files with indirect coverage changes

[damondouglas]

Closing due to duplicate of #1966