Documentation: Mention that KProbes is supported on MIPS

MIPS now has KProbes support, so kprobes.txt should reflect it.
Signed-off-by: David Daney <ddaney@caviumnetworks.com>
To: linux-mips@linux-mips.org
To: ananth@in.ibm.com
To: anil.s.keshavamurthy@intel.com
To: davem@davemloft.net
To: masami.hiramatsu.pt@hitachi.com
Cc: linux-kernel@vger.kernel.org
Cc: hschauhan@nulltrace.org
Patchwork: https://patchwork.linux-mips.org/patch/1527/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

Documentation/kprobes.txt

@@ -285,6 +285,7 @@ architectures:
 - sparc64 (Return probes not yet implemented.)
 - arm
 - ppc
+- mips
 
 3. Configuring Kprobes