docs(workspace): add recommended structure to members field

doc/book/src/reference/workspaces.md

@@ -105,6 +105,10 @@ should be an array of strings containing directories with `Cargo.toml` files.
 The `members` list also supports [globs] to match multiple paths, using
 typical filename glob patterns like `*` and `?`.
 
+**Recommendation:** Keep all member packages in a flat directory (commonly `crates/`)
+and use a glob pattern for the `members` field, e.g.
+`members = ["crates/*"]`. This minimizes churn in maintaining the `members` list.
+
 The `exclude` key can be used to prevent paths from being included in a
 workspace. This can be useful if some path dependencies aren't desired to be
 in the workspace at all, or using a glob pattern and you want to remove a