Update pkg-config recommendation

Signed-off-by: Uilian Ries <[email protected]>

reference/conanfile/attributes.rst

@@ -126,6 +126,7 @@ recipe or the package, then it is possible to exclude them from the check with t
 configuration, which is a list of patterns (fnmatch) to exclude.
 
 
+.. _upload_policy_attribute:
 
 upload_policy
 -------------

reference/tools/gnu/pkgconfig.rst

@@ -47,7 +47,7 @@ Using pkg-config from Conan package instead of system
 
 .. include:: ../../../common/experimental_warning.inc
 
-In case of not having ``pkg-config`` available in the system, it is possible to use the ``pkg-config`` executable provided by a Conan package:
+In case of not having ``pkg-config`` available in the system, it is possible to use the ``pkg-config`` executable provided by Conan ``tool_requires`` instead.:
 
 .. code-block:: python
 
@@ -80,9 +80,12 @@ when consuming the package.
 
 .. warning::
 
-    It's not recommended to use this approach when creating a "system" package recipe, as the packaged information may not be compatible with the host system,
+    It's forbidden to upload or reuse this approach when creating a package, as the information may not be compatible with the host system,
     resulting in errors when consuming the package.
 
+    When using this approach for wrapping system packages, it is recommended to use ``upload_policy = "skip"``
+    (see :ref:`upload_policy_attribute`) in the package recipe to avoid uploading the package.
+
 Reference
 ---------