feat: Add JSON schema, adjust documentation and defaults

[nickdnk]

Adjust error messages
Add documented defaults for FlushBytes

Reason for This PR

Following my work in the roadrunner org where I've been moving all JSON schemas to the repos they belong to, here is that same change for temporal.

Description of Changes

Added JSON schema.
Adjusted some error messages (syntax, grammar) and added default values according to documentation.

License Acceptance

By submitting this pull request, I confirm that my contribution is made under
the terms of the MIT license.

PR Checklist

[Author TODO: Meet these criteria.]
[Reviewer TODO: Verify that these criteria are met. Request changes if not]

• All commits in this PR are signed (git commit -s).
• The reason for this PR is clearly provided (issue no. or explanation).
• The description of changes is clear and encompassing.
• Any required documentation changes (code and docs) are included in this PR.
• Any user-facing changes are mentioned in CHANGELOG.md.
• All added/changed functionality is tested.

[CLAassistant]

All committers have signed the CLA.

[CLAassistant]

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[rustatian]

LGTM, thanks @nickdnk

[codecov-commenter]

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Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 40.06%. Comparing base (c8e0bcf) to head (c5a93ee).
Report is 299 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff             @@
##           master     #570       +/-   ##
===========================================
+ Coverage   22.67%   40.06%   +17.38%     
===========================================
  Files           4       14       +10     
  Lines         269      936      +667     
===========================================
+ Hits           61      375      +314     
- Misses        206      518      +312     
- Partials        2       43       +41     

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