tracing: Kconfig spelling fixes and cleanups

Fix filename reference (ftrace-implementation.txt ->
ftrace-design.txt).

Fix spelling, punctuation, grammar.

Fix help text indentation and line lengths to reduce need for
horizontal scrolling or larger window sizes.

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20091221120117.3fb49cdc.randy.dunlap@oracle.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>