trace doc: convert trace/events-nmi.txt to rst format

This converts the plain text documentation to reStructuredText format and
add it into Sphinx TOC tree. No essential content change.

Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Changbin Du <changbin.du@intel.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/trace/events-nmi.txt → Documentation/trace/events-nmi.rst

+================
 NMI Trace Events
+================
 
 These events normally show up here:
 
 	/sys/kernel/debug/tracing/events/nmi
 
---
 
-nmi_handler:
+nmi_handler
+-----------
 
 You might want to use this tracepoint if you suspect that your
 NMI handlers are hogging large amounts of CPU time.  The kernel
-will warn if it sees long-running handlers:
+will warn if it sees long-running handlers::
 
 	INFO: NMI handler took too long to run: 9.207 msecs
 
@@ -19,7 +21,7 @@ more details.
 
 Let's say you suspect that perf_event_nmi_handler() is causing
 you some problems and you only want to trace that handler
-specifically.  You need to find its address:
+specifically.  You need to find its address::
 
 	$ grep perf_event_nmi_handler /proc/kallsyms
 	ffffffff81625600 t perf_event_nmi_handler
@@ -27,17 +29,17 @@ specifically.  You need to find its address:
 Let's also say you are only interested in when that function is
 really hogging a lot of CPU time, like a millisecond at a time.
 Note that the kernel's output is in milliseconds, but the input
-to the filter is in nanoseconds!  You can filter on 'delta_ns':
+to the filter is in nanoseconds!  You can filter on 'delta_ns'::
 
-cd /sys/kernel/debug/tracing/events/nmi/nmi_handler
-echo 'handler==0xffffffff81625600 && delta_ns>1000000' > filter
-echo 1 > enable
+	cd /sys/kernel/debug/tracing/events/nmi/nmi_handler
+	echo 'handler==0xffffffff81625600 && delta_ns>1000000' > filter
+	echo 1 > enable
 
-Your output would then look like:
+Your output would then look like::
 
-$ cat /sys/kernel/debug/tracing/trace_pipe
-<idle>-0     [000] d.h3   505.397558: nmi_handler: perf_event_nmi_handler() delta_ns: 3236765 handled: 1
-<idle>-0     [000] d.h3   505.805893: nmi_handler: perf_event_nmi_handler() delta_ns: 3174234 handled: 1
-<idle>-0     [000] d.h3   506.158206: nmi_handler: perf_event_nmi_handler() delta_ns: 3084642 handled: 1
-<idle>-0     [000] d.h3   506.334346: nmi_handler: perf_event_nmi_handler() delta_ns: 3080351 handled: 1
+	$ cat /sys/kernel/debug/tracing/trace_pipe
+	<idle>-0     [000] d.h3   505.397558: nmi_handler: perf_event_nmi_handler() delta_ns: 3236765 handled: 1
+	<idle>-0     [000] d.h3   505.805893: nmi_handler: perf_event_nmi_handler() delta_ns: 3174234 handled: 1
+	<idle>-0     [000] d.h3   506.158206: nmi_handler: perf_event_nmi_handler() delta_ns: 3084642 handled: 1
+	<idle>-0     [000] d.h3   506.334346: nmi_handler: perf_event_nmi_handler() delta_ns: 3080351 handled: 1
 

Documentation/trace/index.rst

@@ -15,3 +15,4 @@ Linux Tracing Technologies
    events
    events-kmem
    events-power
+   events-nmi