message: Make it more clear we have two types of workspaces
  It needed a few rereads before I discovered the two flavours. Hope this helps.
diff: A *workspace* is a collection of one or more packages that share common
  dependency resolution (with a shared `Cargo.lock`), output directory, and
  various settings such as profiles. Packages that are part of a workspaces are
  -called *workspace members*.
  +called *workspace members*. There are two flavours of workspaces: as root
  +package or as virtual manifest.
  +
  +### Root package
  A workspace can be created by adding a [`[workspace]`
  section](#the-workspace-section) to `Cargo.toml`. This can be added to a
  @@ -11,11 +14,15 @@ section](#the-workspace-section) to `Cargo.toml`. This can be added to a
  the *root package* of the workspace. The *workspace root* is the directory
  where the workspace's `Cargo.toml` is located.
  +### Virtual manifest
  +
  Alternatively, a `Cargo.toml` file can be created with a `[workspace]` section
  but without a [`[package]` section][package]. This is called a *virtual
  manifest*. This is typically useful when there isn't a "primary" package, or
  you want to keep all the packages organized in separate directories.
  +### Key features
  +
  The key points of workspaces are:
  * All packages share a common `Cargo.lock` file which resides in the
  