doc/develop/sending_patches.rst: Reword where our git tree is slightly

We shouldn't have had the link to our git tree be contained within "``"
as that meant that it did not work as a link, so remove those. And
rather than make this a link plus text, keep this as a link within the
text for overall clarity.

Suggested-by: Quentin Schulz <quentin.schulz@cherry.de>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Reviewed-by: Quentin Schulz <quentin.schulz@cherry.de>
Signed-off-by: Tom Rini <trini@konsulko.com>