Add extra context around required pip flags

Author: dhirschfeld

src/maintainer/adding_pkgs.rst

@@ -363,9 +363,16 @@ while adding ``pip`` to the host requirements:
       host:
         - pip
 
-These options should be used to ensure a clean installation of the package without its
-dependencies. This helps make sure that we're only including this package,
-and not accidentally bringing any dependencies along into the conda package.
+`conda-forge` configures `pip` to ensure a clean installation of the package
+without its dependencies so no extra flags are required to be passed. This
+helps make sure that we're only including this package, and not accidentally
+bringing any dependencies along into the conda package.
+
+.. warning::
+
+    If your package uses `outputs` you may have to manually specify the flags
+    `--no-deps --no-build-isolation` due to a bug in `conda-build`. See
+    https://github.com/conda/conda-build/issues/3993
 
 Usually pure-Python packages only require ``python``, ``setuptools`` and ``pip``
 as ``host`` requirements; the real package dependencies are only