Make a new more obvious Tutorial for editing paths

Issue from twitter: https://twitter.com/Snoozriel/status/1305980522162601986

Summary:

Currently the tutorial for path editing functionality in Inkscape which is very important to many Inkscape users is hidden behind the Tutorial marked "Advanced", it's contained within a section that's not obvious as well as being mixin in with other items.

Steps to reproduce:

• open Inkscape
• Help > Tutorials > ...

What happened?

Couldn't find tutorial on editing paths / couldn't learn how to use paths from the tutorials

What should have happened?

Help > Tutorials > Path Editing

I propose the path editing features be split out of the Advanced tutorial into their own. They should be expanded upon and made more useful, showing node editing, the node types and some of the features such as paralax, connectors, etc.

The advanced might end up a bit slim, but we have new features like css editor and some others which might be good to add here. (maybe another issue for this)

Please move to the docs project if there's enough support.