Add README and update pm-graph and sleepgraph docs

Config/man page/README files:
 - include README in the pm-graph folder
 - add more detail to the example config to describe more options
 - update the sleepgraph man page to document the new arguments

Signed-off-by: Todd Brandt <todd.e.brandt@linux.intel.com>
[ rjw: Subject ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

tools/power/pm-graph/config/example.cfg

@@ -98,12 +98,34 @@ postdelay: 0
 # graph only devices longer than min in the timeline (default: 0.001 ms)
 mindev: 0.001
 
+# Call Loop Max Gap (dev mode only)
+# merge loops of the same call if each is less than maxgap apart (def: 100us)
+callloop-maxgap: 0.0001
+
+# Call Loop Max Length (dev mode only)
+# merge loops of the same call if each is less than maxlen in length (def: 5ms)
+callloop-maxlen: 0.005
+
+# Override default timeline entries:
+# Do not use the internal default functions for timeline entries (def: false)
+# Set this to true if you intend to only use the ones defined in the config
+override-timeline-functions: true
+
+# Override default dev timeline entries:
+# Do not use the internal default functions for dev timeline entries (def: false)
+# Set this to true if you intend to only use the ones defined in the config
+override-dev-timeline-functions: true
+
 # ---- Debug Options ----
 
 # Callgraph
 # gather detailed ftrace callgraph data on all timeline events (default: false)
 callgraph: false
 
+# Max graph depth
+# limit the callgraph trace to this depth (default: 0 = all)
+maxdepth: 2
+
 # Callgraph phase filter
 # Only enable callgraphs for one phase, i.e. resume_noirq (default: all)
 cgphase: suspend
@@ -131,3 +153,7 @@ timeprec: 6
 # Add kprobe functions to the timeline
 # Add functions to the timeline from a text file (default: no-action)
 # fadd: file.txt
+
+# Ftrace buffer size
+# Set trace buffer size to N kilo-bytes (default: all of free memory up to 3GB)
+# bufsize: 1000