[BUG] Link to the documentation in the README is not valid #405

Describe the bug
In the README there is a link to the documentation, which is not valid.
Instead of https://tinyauth.app/docs/getting-started
the link is: https://tinyauth.app/docs/getting-started.html
which leads to a 404 error (page not found).

To Reproduce

1. Go to https://github.com/steveiliop56/tinyauth
2. Click on 'documentaion' in the chapter "Getting started"
3. See error: Page not found

Expected behavior
The link should be correct to access the documentation.