Supplement the content about membership in the root package

Author: heisen-li

src/doc/src/reference/workspaces.md

@@ -33,10 +33,6 @@ In the `Cargo.toml`, the `[workspace]` table supports the following sections:
 * [`[replace]`](overriding-dependencies.md#the-replace-section) --- Override dependencies (deprecated).
 * [`[profile]`](profiles.md) --- Compiler settings and optimizations.
 
-## Creating a Workpaces
-
-todo!：Added example of creating a workspace.
-
 ## The `[workspace]` section
 
 To create a workspace, you add the `[workspace]` table to a `Cargo.toml`:
@@ -55,7 +51,6 @@ If the [`[workspace]` section](#the-workspace-section) is added to a
 the *root package* of the workspace. 
 
 Example:
-
 ```toml
 [workspace]
 
@@ -65,6 +60,9 @@ version = "0.1.0"    # the current version, obeying semver
 authors = ["Alice <[email protected]>", "Bob <[email protected]>"]
 ```
 
+Under [workspace](#the-workspace-section), you can specify which members the workspace has through 
+[workspace.members filed](#the-members-and-exclude-fields) .
+
 If no other members are specified in [workspace.members filed](#the-members-and-exclude-fields) 
 in `Cargo.toml` in the workspace root directory, the root package will 
 become the default workspace member.