Add warning about pip ignoring lock files (#8117)

docs/basic-usage.md

@@ -234,6 +234,10 @@ Even if you develop alone, in six months when reinstalling the project you can f
 the dependencies installed are still working even if your dependencies released many new versions since then.
 the dependencies installed are still working even if your dependencies released many new versions since then.
 (See note below about using the update command.)
 (See note below about using the update command.)
 
 
+{{% warning %}} If you have added the recommended [`[build-system]`]({{< relref "pyproject#poetry-and-pep-517" >}}) section to your project's pyproject.toml then you _can_ successfully install your project and its dependencies into a virtual environment using a command like `pip install -e .`. However, pip will not use the lock file to determine dependency versions as the poetry-core build system is intended for library developers (see next section).
+{{% /warning %}}
+
+
 #### As a library developer
 #### As a library developer
 
 
 Library developers have more to consider. Your users are application developers, and your library will run in a Python environment you don't control.
 Library developers have more to consider. Your users are application developers, and your library will run in a Python environment you don't control.