Make the nav panel on the left collapsible

[mojavelinux]

Add a button that allows the reader to collapse the nav panel on the left. On certain screen sizes, this gives the reader more room to read the content. An icon should remain (perhaps in a narrow bar) that can be used to expand it again.

[mojavelinux]

Examples for reference:

• https://docs.couchbase.com/server/current/introduction/intro.html
• https://docs.confluent.io/platform/current/clients/index.html
• https://docs.aws.amazon.com/AmazonS3/latest/gsg/GetStartedWithS3.html

I think it works best when the setting is persistent. Otherwise, the user constantly has to fiddle with it.

[mojavelinux]

I'm not convinced how useful this is. It's actually pretty hard to find examples of this pattern in use.