Create doc.odin

Create a doc file with a brief of the package and an example program (copied from a discord message by laytan)

core/container/intrusive/list/doc.odin

@@ -0,0 +1,39 @@
+/*
+Package list implements an intrusive doubly-linked list.
+
+An intrusive container requires a `Node` to be embedded in your own structure, like this:
+
+	My_String :: struct {
+		node:  list.Node,
+		value: string,
+	}
+
+Here is a full example:
+
+	package test
+	
+	import "core:fmt"
+	import "core:container/intrusive/list"
+	
+	main :: proc() {
+	    l: list.List
+	
+	    one := My_String{value="Hello"}
+	    two := My_String{value="World"}
+	
+	    list.push_back(&l, &one.node)
+	    list.push_back(&l, &two.node)
+	
+	    iter := list.iterator_head(l, My_String, "node")
+	    for s in list.iterate_next(&iter) {
+	        fmt.println(s.value)
+	    }
+	}
+	
+	My_String :: struct {
+	    node:  list.Node,
+	    value: string,
+	}
+
+*/
+package container_intrusive_list