Using a named pane will cause default renderer to not be used

[nemosmithasf]

I'm pretty sure this is a bug, but I don't know enough about the codebase, so I'll file this as "needing documentation".

Here is the relevant snippet in the codebase:

Leaflet/src/layer/vector/Renderer.js

Lines 122 to 127 in db7482a

	if (!renderer) {
	// @namespace Map; @option preferCanvas: Boolean = false
	// Whether `Path`s should be rendered on a `Canvas` renderer.
	// By default, all `Path`s are rendered in a `SVG` renderer.
	renderer = this._renderer = (this.options.preferCanvas && L.canvas()) || L.svg();
	}

The problem

If the layer is a named pane, then the code will automatically create a renderer for the pane if none exists.

This is a problem however, because if we added a default renderer (i.e. during Map creation), it will get ignored.

Suggested changes

Fill in the documentation.

[syonfox]

https://leafletjs.com/reference.html#path-renderer

Just a random idea also not an expert. but the wording here sounds like

renderer 	[Renderer](https://leafletjs.com/reference.html#renderer) 		

Use this specific instance of [Renderer](https://leafletjs.com/reference.html#renderer) for this path. Takes precedence over the map's [default renderer](https://leafletjs.com/reference.html#map-renderer).

I suppose you could override the render after map creation on a path by path basis. this would allow control of layers as well.