[PATCH v2 2/3] Documentation: explain how safe.directory works when running under sudo

["Carlo Marcelo Arenas Belón" <carenas@gmail.com>]

In a previous patch, the behavior of git was changed so it will be able
to find the "effective uid" that is required when git was invoked with
sudo to root, for example the internal calls made to git when calling
the following in git's own repository:

  $ sudo make install

Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 Documentation/config/safe.txt | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/Documentation/config/safe.txt b/Documentation/config/safe.txt
index 6d764fe0ccf..ee558ced8c7 100644
--- a/Documentation/config/safe.txt
+++ b/Documentation/config/safe.txt
@@ -26,3 +26,12 @@ directory was listed in the `safe.directory` list. If `safe.directory=*`
 is set in system config and you want to re-enable this protection, then
 initialize your list with an empty value before listing the repositories
 that you deem safe.
++
+When git tries to check for ownership of git repositories, it will
+obviously do so with the uid of the user that is running git itself,
+but if git is running as root, it will check first if it might have
+been started through `sudo`, and if that is the case, will instead
+use the uid of the user that did so.
+If that is not what you would prefer and want git to only trust
+repositories that are owned by root instead, then you should remove
+the `SUDO_UID` variable from root's environment.
-- 
2.36.0.352.g0cd7feaf86f