docs/manual/using-buildroot-toolchain.adoc: fix overridden typo

Overridden is with double-r-double-d.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

docs/manual/using-buildroot-toolchain.adoc

@@ -16,7 +16,7 @@ Alternatively, Buildroot can also export the toolchain and the development
 files of all selected packages, as an SDK, by running the command
 +make sdk+. This generates a tarball of the content of the host directory
 +output/host/+, named +<TARGET-TUPLE>_sdk-buildroot.tar.gz+ (which can be
-overriden by setting the environment variable +BR2_SDK_PREFIX+) and
+overridden by setting the environment variable +BR2_SDK_PREFIX+) and
 located in the output directory +output/images/+.
 
 This tarball can then be distributed to application developers, when