Update documentation for new `pkgid` attribute.

1 files changed, 4 insertions, 3 deletions

diff --git a/doc/rustpkg.md b/doc/rustpkg.md
index 1b1f91828cb..ff413ec1f1b 100644
--- a/doc/rustpkg.md
+++ b/doc/rustpkg.md
@@ -89,6 +89,10 @@ as well as `foo/src/bar/extras/baz/lib.rs`,
 then both `bar` and `bar/extras/baz` are valid package identifiers
 in the workspace `foo`.
 
+Because rustpkg uses generic source file names as the main inputs, you will
+need to specify the package identifier in them using the `pkgid` attribute
+on the crate.
+
 ## Source files
 
 rustpkg searches for four different fixed filenames in order to determine the crates to build:
@@ -108,9 +112,6 @@ When building a package that is not under version control,
 or that has no tags, `rustpkg` assumes the intended version is 0.1.
 
 > **Note:** A future version of rustpkg will support semantic versions.
-> Also, a future version will add the option to specify a version with a metadata
-> attribute like `#[link(vers = "3.1415")]` inside the crate module,
-> though this attribute will never be mandatory.
 
 # Dependencies