Documentation: Update tracepoint-analysis.txt

Fix grammar, spelling, punctuation, hyphenation, section
numbering. Tell what PCL means.

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <4B2C0D70.4030707@oracle.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>