docs Add Functions to Existing Tutorial

Describe the change you'd like to see The existing tutorial does not include Knative Functions. It would be nice to have something there by KubeCon in October. This request is to add a section in the left-hand menu called "Using Knative Functions" or similar which is an introduction to the technology, including a tutorial.

Additional context For the time being, this supercedes https://github.com/knative/docs/issues/5038 as it will be easier and quicker to complete by the end of October. Leaving 5038 open, however, for long-range planning.

An example of the proposed section

/kind enhancement /kind functions

Aug 30 '22 19:08 lance

Not sure if this link is related? https://miro.com/app/board/o9J_lAlC520=/ I don't know who owns this doc, just found it when I was clearing out bookmarks

Sep 07 '22 12:09 abrennan89

Not sure if this link is related? https://miro.com/app/board/o9J_lAlC520=/ I don't know who owns this doc, just found it when I was clearing out bookmarks

I cannot access the link

Sep 07 '22 20:09 lance