[PATCH] docs: rust: Clarify that 'rustup override' applies to build directory

[Viresh Kumar]

Rustup override is required to be set for the build directory and not
necessarily the kernel source tree (unless the build directory is its
subdir).

Clarify the same in quick-start guide.

Signed-off-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
---
 Documentation/rust/quick-start.rst | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/Documentation/rust/quick-start.rst b/Documentation/rust/quick-start.rst
index f382914f4191..a7a08955fe46 100644
--- a/Documentation/rust/quick-start.rst
+++ b/Documentation/rust/quick-start.rst
@@ -39,8 +39,13 @@ If ``rustup`` is being used, enter the checked out source code directory
 	rustup override set $(scripts/min-tool-version.sh rustc)
 
 This will configure your working directory to use the correct version of
-``rustc`` without affecting your default toolchain. If you are not using
-``rustup``, fetch a standalone installer from:
+``rustc`` without affecting your default toolchain.
+
+Note that the override applies to the build directory (and its sub-directories).
+If the kernel is built with `O=<build directory>`, the override must be set for
+the build directory instead.
+
+If you are not using ``rustup``, fetch a standalone installer from:
 
 	https://forge.rust-lang.org/infra/other-installation-methods.html#standalone
 
-- 
2.31.1.272.g89b43f80a514