docs: fix modifiers link

[fty4]

Description

• modifiers: link starting with a capital letter only works on GitHub Markdown - not within readthedocs.io
• backends: link with single dot will not forward to page on readthedocs.io

(tested with Chrome, Windows, Firefox, Ubuntu)

This PR change will only fix two hyperlink.

Fixes:

• fix hyperlink (anker) on same page to Modifiers - using lower case
• fix hyperlink to backends page - using two dots as already in use

Checklist

Please make sure that your PR fulfills the following requirements:

• Reviewed the guidelines for contributing to this repository
• The commit message follows the Conventional Commits Guidelines.
• Tests for the changes have been updated
• Docs have been added / updated
• Optional. My organization is added to USERS.md.

Type of Change

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• New tests
• Build/CI related changes
• Documentation content changes
• Other (please describe)

[CLAassistant]

All committers have signed the CLA.

[werne2j]

Thanks @fty4! If you could resolve the conflicts, we can continue with the review process.

[werne2j]

Thanks @fty4! If you could resolve the conflicts, we can continue with the review process.

[fty4]

@werne2j solved the merge conflict

[werne2j]

Thanks @fty4!