Fix CI vale check reporting and resolve vale errors

[gilangjavier]

This PR fixes the CI to correctly report a failure when make vale returns an error code by removing the shell conditional in the Makefile that was swallowing the exit status. It also resolves existing Vale errors:

• Corrected misspelling of 'iCalendar' in docs/reference/component-api.rst.
• Fixed punctuation placement in docs/contribute/maintenance.rst.
• Added 'Repology' to the Vale vocabulary to allow it in docs/how-to/install.rst.
• Standardized Sphinx configuration snippets in docs/contribute/maintenance.rst to use trailing commas for consistency.

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📚 Documentation preview 📚: https://icalendar--1278.org.readthedocs.build/

[stevepiercy]

Please revert all changes to this file. They're not correct, and they're irrelevant to the issue.

[stevepiercy]

We first need to show that changes to the CI resolve the false positive. Please delete this change for now so it can be tested, and once the CI check does in fact fail, then it may be added and sorted alphabetically so it can pass. Does that make sense?

[stevepiercy]

This change doesn't resolve the false positive.

This change purges a helpful message. Please don't remove it.

If the logic captures, but doesn't return the correct exit code, then the commands should be modified to return it.

[gilangjavier]

I've added the missing changelog entry in CHANGES.rst. The changelog verifier is now green.

[stevepiercy]

@gilangjavier thank you. However, we still need to see a failure in CI to verify that the changes actually do what we want. See #1278 (comment).