Docs: linking files in master branch

[vitek-rostislav]

Describe the bug

There are various links across the documentation that point to the files in the master branch. The master branch is not the main branch anymore so the linked files might be outdated.

• We should update the links properly (use the current main branch instead - 14.0 at the moment).
• CheckDocsReleaseWorker should be modified to ensure the links are updated during the release process.

// EDIT: maybe the best way would be to use the latest build on read the docs, e.g. https://docs.shopsys.com/en/latest/contributing/