Add reference for proper linking

Add reference in index.rst so propoer linking can be accomplish for other readthedocs pages.

Issue-ID: DOC-203

Change-Id: I484f018f6ac4745df9d4df8e9ef61418e8312d2a
Signed-off-by: Gildas Lanilis <gildas.lanilis@huawei.com>
1 file changed