Updated fsdocs-tool to v20 stable

[Thorium]

After build spending around 6h in document generation, there was an idea to update the fsdocs-tool:
#1496 (comment)

[nojaf]

It seems to get stuck on generating model for docs\library\JsonProvider.fsx --> .\library\JsonProvider.html.

[Thorium]

It does work on Ubuntu CI, and it does work on local Windows.
It could be multiple things, e.g.:

• Some network-request blocked
• Some source code issue (but why would it work locally?)
• Something incorrect in the comment-syntax (but it looks a lot like CsvProvider.fsx which does work)

Edit: I tested to disconnect my local computer from the internet and JsonProvider.fsx generation still worked.

[nojaf]

I can't build on my Windows, so can't tell what is up.

[Thorium]

Now it works.

Either:

• The >> was too acidic for the fsdocs-tool, or
• the array-indexing without . was too recent syntax for this project.

[cartermp]

Hrm, I'm surprised fsdocs would not like this, but hey, if it unblocks us then it unblocks us. Thanks so much for digging into this @Thorium