README: Update OpenZFS website url

This change is to first replace the OpenZFS website in the README to
point to openzfs.org as this is what open-zfs.org redirects to.
Along with replacing the URL, the protocol is also upgraded
from http to https.

These changes should prevent web browsers such as Firefox from
complaining about visiting a http site, if the proper security
settings are enabled, when it will still end up on a https page
after the redirect.

Reviewed-by: George Melikov <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Ryan Hirasaki <[email protected]>
Closes #12939

README.md

@@ -12,7 +12,7 @@ This repository contains the code for running OpenZFS on Linux and FreeBSD.
   * [Documentation](https://openzfs.github.io/openzfs-docs/) - for using and developing this repo
   * [ZoL Site](https://zfsonlinux.org) - Linux release info & links
   * [Mailing lists](https://openzfs.github.io/openzfs-docs/Project%20and%20Community/Mailing%20Lists.html)
-  * [OpenZFS site](http://open-zfs.org/) - for conference videos and info on other platforms (illumos, OSX, Windows, etc)
+  * [OpenZFS site](https://openzfs.org/) - for conference videos and info on other platforms (illumos, OSX, Windows, etc)
 
 # Installation