Documentation: siphash: convert danger note to warning for HalfSipHash

Render danger paragraph into warning block for emphasization.

Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Eric Biggers <ebiggers@google.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Bagas Sanjaya <bagasdotme@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

Author: bagasme

Documentation/security/siphash.rst

@@ -121,12 +121,12 @@ even scarier, uses an easily brute-forcable 64-bit key (with a 32-bit output)
 instead of SipHash's 128-bit key. However, this may appeal to some
 high-performance `jhash` users.
 
-Danger!
-
-Do not ever use HalfSipHash except for as a hashtable key function, and only
-then when you can be absolutely certain that the outputs will never be
-transmitted out of the kernel. This is only remotely useful over `jhash` as a
-means of mitigating hashtable flooding denial of service attacks.
+.. warning::
+   Do not ever use HalfSipHash except for as a hashtable key function, and
+   only then when you can be absolutely certain that the outputs will never
+   be transmitted out of the kernel. This is only remotely useful over
+   `jhash` as a means of mitigating hashtable flooding denial of service
+   attacks.
 
 Generating a HalfSipHash key
 ============================