--- a/libpam-sys/libpam-sys-consts/README.md	Wed Jul 09 16:59:30 2025 -0400
+++ b/libpam-sys/libpam-sys-consts/README.md	Sat Jul 12 17:17:37 2025 -0400
@@ -49,11 +49,16 @@
 
 ## Configuration
 
-By default, this crate automatically detects your libpam version.
-Known implementations are listed in the `PamImpl` enum.
+Known implementations of PAM are listed in the `PamImpl` enum, and your currently installed implementation is automatically detected.
+
+If you need to configure this, you can override it **at build time** with the `LIBPAMSYS_IMPL` environment variable:
 
-You can override this **at build time** by setting the `LIBPAMSYS_IMPL` environment variable to one of those names.
-For example, `LIBPAMSYS_IMPL=OpenPam cargo build` will build this library for OpenPAM.
+- Unset or `` (the default): Probe the currently installed LibPAM to figure out which implementation it is.
+  If LibPAM is not present, this will fall back to `__TARGET_DEFAULT__`.
+- `__TARGET_DEFAULT__`: Select the version of LibPAM most likely to be installed on the current OS.
+  This is a useful setting for cross-compiling.
+- The name of a `PamEnum` entry: The named PAM implementation.
+  For instance, `LIBPAMSYS_IMPL=OpenPam cargo build` will build this library for OpenPAM.
 
 ## MSRV