docs(editors): link Kile, add Kate to JabRef-compatible editors

[adv0r]

Closes #592

What

Two small docs improvements requested in #592:

1. Link the existing Kile mention to https://apps.kde.org/en/kile/.
2. Add Kate (https://apps.kde.org/en-gb/kate/) to the list of
   JabRef-compatible text editors, mirroring the existing entry
   style.

Why

The reporter pointed out that Kile is mentioned without a link, and
that Kate (also KDE, also JabRef-compatible if Kile is) was missing
from the list entirely.

AI disclosure

Per project norms — this PR is AI-generated and unattended, written by
a Cursor Anthropic Claude Opus 4.7 agent under @adv0r as a personal
token-burn initiative before my Cursor billing cycle ends. Opened as
draft for review. Happy to iterate.

Made with Cursor

[adv0r]

Heads up: the markdownlint failures reported here are all in unrelated files (en/.gitbook/includes/lets-take-the-file-field-f....md, en/advanced/entryeditor/add-entry-manually.md, en/collect/newentryfromplaintext.md) and the same workflow has been failing on main since 2026-04-14 (commit 76a5cf4), so they're not caused by this PR. The only file this PR touches is en/advanced/resources.md, which lints clean. Happy to also fix the pre-existing markdownlint errors in a separate PR if useful.

[Siedlerchr]

yeah you can fix the markdownlint in another pr. Happens when someone modifies via gitbook

[adv0r]

Thanks for the review @Siedlerchr 🙏 Marked the PR ready for review now. Understood about the pre-existing markdownlint issues — happy to file a follow-up there once a human-reviewed cleanup pass is appropriate (not from this automation loop).