Ballista 0.8.0 Release

[andygrove]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.
It has been a few months since the last Ballista release, so I proposed we release 0.8.0 soon. This issue is for tracking the work that needs to happen.

• Update User Guide #160
• Update README to better reflect project status
• Add release scripts for the Python bindings
• Upgrade to DataFusion 11.0.0 #163
• Upgrade to DataFusion 12.0.0
• Create the release
• Publish the user guide to the Arrow website

Describe the solution you'd like
See above.

Describe alternatives you've considered
None

Additional context
None

[andygrove]

@yahoNanJing @thinkharderdev @avantgardnerio I plan on creating the next release on Friday (Septemeber 16). Is there anything you would like to try and get in before I do this? If so, could you please add to the checklist in this issue,

[avantgardnerio]

try and get in before I do this?

Sadly, with our deltalake setback, we'll be waiting on 0.9.0 now. This release will allow us to upstream the rest of the FlightSQL implementation however.

[yahoNanJing]

A few improvements still left according to apache/datafusion#3493. However, I think we can go to the 0.9.0 for them