Switch from GitBook to just-the-docs theme

[koppor]

Years ago, we switched from markdown file rendering to the GitBook service for https://devdocs.jabref.org (source: https://github.com/JabRef/jabref/tree/main/docs). There, we gained a) WYSIWG editors, b) instant search, c) insights on pages views, and d) user ratings. We "payed" with a) continuous renaming of images, b) difficulties in synchronization (stopped working after a few months) and c) sometimes strange markup.

Example for c) and d)

I found just-the-docs markdown theme. It offers a) instant search, b) site analytics (using google analytics) and is "just" a static web page.

IMHO we had no contributions using GitBook and only issues. Thus, I propose to switch back to plain Markdown.

Screenshot: left: GitBook, right: just-the-docs theme

• Change in CHANGELOG.md described in a way that is understandable for the average user (if applicable)
• Tests created for changes (if applicable)
• Manually tested changed features in running JabRef (always required)
• Screenshots added in PR description (for UI changes)
• Checked developer's documentation: Is the information available and up to date? If not, I outlined it in this pull request.
• Checked documentation: Is the information available and up to date? If not, I created an issue at https://github.com/JabRef/user-documentation/issues or, even better, I submitted a pull request to the documentation repository.

[Siedlerchr]

Then don't forget to remove the gitbook integration