Readme update

[nathanlcarlson]

No description provided.

[nathanlcarlson]

The version has been bumped to v3.0b1 in the documentation for the release to be.
Changes have been made to these two pages:
https://esgf.github.io/esgf-installer/autoinstall_usage.html
and
https://esgf.github.io/esgf-installer/installation.html

[nathanlcarlson]

The usage page now has also been updated using sphinx-argparse. https://esgf.github.io/esgf-installer/usage.html

[William-Hill]

Is this still WIP or is it ready for review?

[nathanlcarlson]

Go ahead and checkout those updated sphinx pages and the README here in the repo and let me know what you think. There was one thing I wanted to test so I will merge if that works out okay.

[nathanlcarlson]

The test I did turned okay. Let me know what you think.

[William-Hill]

@nathanlcarlson 2 suggested changes on the README: 1) change "ESGF.org" to just "ESGF". I don't think we have control of esgf.org anymore. 2) Add mention of the migrate option for the bootstrap. Something like "If you are migrating to ESGF 3.0 from a previous version of ESGF, add the migrate parameter to the the bootstrap ./esg_bootstrap.sh migrate

[William-Hill]

@nathanlcarlson Docs pages look really good. I would double check with @sashakames to see if the options we marked as deprecated can go ahead and be removed from the doc pages