Fix broken link: Remove reference to non-existent dynamic_quantizatio…

[patrocinio]

…n recipe

The dynamic_quantization.py recipe file does not exist in the repository, causing a 404 error when accessing the URL: https://pytorch.org/tutorials/recipes/recipes/dynamic_quantization.html

Removed references to this missing recipe from:

• recipes_index.rst
• recipes_source/recipes/README.txt

Also renumbered subsequent items in README.txt to maintain sequential numbering.

Fixes #3503

Fixes #ISSUE_NUMBER

Description

Checklist

• [ ] The issue that is being fixed is referred in the description (see above "Fixes #ISSUE_NUMBER")
• [ ] Only one issue is addressed in this pull request
• [ ] Labels from the issue that this PR is fixing are added to this pull request
• [ ] No unnecessary issues are included into this pull request.

cc @svekars @sekyondaMeta @AlannaBurke