typo: correct "Release behaviour" in the configuration guide

[veyxov]

should be all-released instead of last-release which doesn't exist

Describe your changes. Use imperative present tense.

fixed typo

Checklist

• Add documentation to docs/config.adoc
  • [x] Yes or N/A
• Add example and basic docs to cfg_samples/kanata.kbd
  • [x] Yes or N/A
• Update error messages
  • [x] Yes or N/A
• Added tests, or did manual testing
  • [ ] Yes

[jtroo]

Thanks!