perf Documentation: sysfs events/ interfaces

perf Documentation: sysfs events/ interfaces

Add documentation for the <event>, <event>.scale, and <event>.unit
files in sysfs.

	<event>.scale and <event>.unit were undocumented.
	<event> was previously documented only for specific powerpc pmu events.

Signed-off-by: Cody P Schafer <[email protected]>
Signed-off-by: Sukadev Bhattiprolu <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Anshuman Khandual <[email protected]>
Cc: Cody P Schafer <[email protected]>
Cc: Haren Myneni <[email protected]>
Cc: Haren Myneni <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Stephane Eranian <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>