Convert the TLS doc to RST.  Use C code blocks for the code
samples, and mark hyperlinks.
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: NDave Watson <davejwatson@fb.com>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>