message: Mention "private" in publish field docs
diff: @@ -166,7 +166,8 @@ migration.
  #### The `publish` field (optional)
  The `publish` field can be used to prevent a package from being published to a
  -package registry (like *crates.io*) by mistake.
  +package registry (like *crates.io*) by mistake, for instance to keep a package
  +private in a company.
  ```toml
  [package]
  