Broken stack install instruction link markdown syntax in README.md

[viljamivirolainen]

You can install stack following the instructions here: (https://docs.haskellstack.org/en/stable/install_and_upgrade/)[https://docs.haskellstack.org/en/stable/install_and_upgrade/]

Which is rendered as a weird broken url like this:

(https://docs.haskellstack.org/en/stable/install_and_upgrade/)[https://docs.haskellstack.org/en/stable/install_and_upgrade/]

Should be either:

You can install stack following the instructions here: [https://docs.haskellstack.org/en/stable/install_and_upgrade/] (https://docs.haskellstack.org/en/stable/install_and_upgrade/)

Or just:

https://docs.haskellstack.org/en/stable/install_and_upgrade/

Both render the same working link:

https://docs.haskellstack.org/en/stable/install_and_upgrade/
https://docs.haskellstack.org/en/stable/install_and_upgrade/