docs: changelog for large skill previews

CHANGELOG.md

@@ -51,6 +51,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - ⚠️ **Database Migrations**: This release includes database schema changes; we strongly recommend backing up your database and all associated data before upgrading in production environments. If you are running a multi-worker, multi-server, or load-balanced deployment, all instances must be updated simultaneously, rolling updates are not supported and will cause application failures due to schema incompatibility.
 - 💡 **Follow-ups as next messages.** The default follow-up prompt now suggests the messages you would most likely send next, in your own tone and latest language, as requests or questions, without repeating finished work, with the strongest suggestion first, and reads only the chat's first message and the last four, each cut to 1,000 characters, so long chats stay quick, where it asked for questions only over the last six messages; instances with a custom follow-up prompt are not affected. [Commit](https://github.com/open-webui/open-webui/commit/7ae09967459151433be79c2e98f096c171fc5b18), [Commit](https://github.com/open-webui/open-webui/commit/53a8f131f305a3beb87376d5dbc05889883fb950)
+- 📖 **Large skills load as a preview.** With the Skills builtin tools on, a skill whose SKILL.md is longer than 20,000 characters now reaches the model as a 5,000 character opening preview with a list of its sections, and the model reads the sections it needs with read_skill_file, which now returns up to 20,000 characters per call instead of 100,000, keeping long skills from filling the context. [Commit](https://github.com/open-webui/open-webui/commit/200b9514917a070c88d112e3c0aba9df3322c5e1)
 
 ## [0.12.0] - 2026-10-10