Fix README symlink

[ipetkov]

Motivation

Checklist

• added tests to verify new behavior
• added an example template or updated an existing one
• updated docs/API.md (or general documentation) with changes
• updated CHANGELOG.md

[dpc]

I can't tell what changed. :D

[ipetkov]

Heh that's because git tends to visualize symlinks as a path to where they link

At some point I ran some sed script to do some bulk *.md replacing and I think it ended up replacing the symlink with a file which had the contents ../README.md. This resulted in the main page of the docs rendering... well, ../README.md

But now its an actual symlink and the docs are rendering fine