Mention uv pip behavior in build system note (#9586)

xref #9518

docs/concepts/projects/config.md

@@ -116,8 +116,8 @@ with the default build system.
     the presence of a `[build-system]` table is not required in other packages. For legacy reasons,
     if a build system is not defined, then `setuptools.build_meta:__legacy__` is used to build the
     package. Packages you depend on may not explicitly declare their build system but are still
-    installable. Similarly, if you add a dependency on a local package, uv will always attempt to
-    build and install it.
+    installable. Similarly, if you add a dependency on a local package or install it with `uv pip`,
+    uv will always attempt to build and install it.
 
 ## Project packaging