doc: board/qualcomm: link to APQ8016 TRM

The MSM8916/APQ8016 Technical Reference Manual is publicly available and
contains a lot of useful register maps for many core parts of the SoC.
Include an archive.org link to it in the dragonboard410c documentation.

Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Reviewed-by: Sumit Garg <sumit.garg@linaro.org>
Signed-off-by: Caleb Connolly <caleb.connolly@linaro.org>
diff --git a/doc/board/qualcomm/dragonboard410c.rst b/doc/board/qualcomm/dragonboard410c.rst
index d0de9db..3462924 100644
--- a/doc/board/qualcomm/dragonboard410c.rst
+++ b/doc/board/qualcomm/dragonboard410c.rst
@@ -14,6 +14,8 @@
 
 .. _96Boards product page: https://www.96boards.org/product/dragonboard410c/
 
+.. _MSM8916/SD410/APQ8016 Technical Reference Manual: https://web.archive.org/web/20210525022203/https://developer.qualcomm.com/qfile/35259/lm80-p0436-100_d_snapdragon_410e_apq8016e_tech_reference_manual_revd.pdf
+
 Installation
 ------------
 First, setup ``CROSS_COMPILE`` for aarch64. Then, build U-Boot for ``dragonboard410c``::