All kernel document now are changed to rst format

which means the links of all *.txt link is invalid now

The issue is about broken links in the book's documentation after a format change from .txt to .rst. Start by finding all .txt file references in the repository, likely in markdown or rst files. Use grep or a script to locate them, then update each link to point to the corresponding .rst file. Verify by building the documentation locally to ensure links work.

Vom Indexierungsmodell aus dem Issue-Text verfasst.