[Module std.container.rbtree] inadequate documentation

[dlangBugzillaToGithub]

mark reported this on 2020-03-07T15:38:48Z

Transfered from https://issues.dlang.org/show_bug.cgi?id=20646

Description

Every one of the examples shown at the top of the page uses the redBlackTree function which takes a sequence of items.

There isn't a single example that begins with an empty tree or that uses new. Yet, because RedBlackTree is a class, you _must_ use new to create a new empty tree.

I think there should be at least one example showing how to create an empty tree, and then populate it with some values.