Website updates (from oct 2020)

[Shazwazza]

Streamlines some of the build operations:

• Uses powershell flags instead of 0/1
• Updates docs on how to run the scripts including their params
• re-enables our docfx plugins with custom MD parsers so the lucene version is automatically applied throughout the docs
• Ensures the correct base path is used when building the docs for release so that linking works correctly

I have run this locally and the docs build so perhaps it fixes this? #380

[NightOwl888]

Thanks. This takes care of #380.

I added a fix for trimming the trailing slash if the user enters one and also a hack for setting the environment variable, since the plugin doesn't read it from the command line version.

There are still a lot of links that aren't resolving (example 1, example 2, example 3), but this is not a new issue.