message: Clarify docs on workspace members
diff: @@ -457,10 +457,12 @@ as:
  ```toml
  [workspace]
  -# Optional key, inferred if not present
  +# Optional key, inferred from path dependencies if not present.
  +# Additional non-path dependencies that should be included must be given here.
  +# In particular, for a virtual manifest, all members have to be listed.
  members = ["path/to/member1", "path/to/member2", "path/to/member3/*"]
  -# Optional key, empty if not present
  +# Optional key, empty if not present.
  exclude = ["path1", "path/to/dir2"]
  ```
  