Arrow: Docs with .MD extension (caps) fail to be edited

[pakoito]

Repro:

Go to https://arrow-kt.io/docs/optics/index/
Click Edit on the top right
BROKEN LINK
Edit url from .md to .MD
Fixed!

Fix:
Rename all .MD files to .md

https://github.com/arrow-kt/arrow/blob/master/modules/docs/arrow-docs/docs/docs/effects/promise/README.MD
https://github.com/arrow-kt/arrow/blob/master/modules/docs/arrow-docs/docs/docs/optics/filterindex/README.MD
https://github.com/arrow-kt/arrow/blob/master/modules/docs/arrow-docs/docs/docs/effects/fiber/README.MD
https://github.com/arrow-kt/arrow/blob/master/modules/docs/arrow-docs/docs/docs/optics/index/README.MD
https://github.com/arrow-kt/arrow/blob/master/modules/docs/arrow-docs/docs/docs/optics/snoc/README.MD
https://github.com/arrow-kt/arrow/blob/master/modules/docs/arrow-docs/docs/docs/optics/cons/README.MD
https://github.com/arrow-kt/arrow/blob/master/modules/docs/arrow-docs/docs/docs/effects/ref/README.MD

[pedrovgs]

I'm fixing this one @pakoito 😃

[pakoito]

🎉