Documentation: cpu-idle-cooling: fix a SEVERE docs build failure

Sphinx ('make htmldocs') stops with a SEVERE error:

Sphinx parallel build error:
SystemMessage: /home/rdunlap/lnx/next/linux-next-20200120/Documentation/driver-api/thermal/cpu-idle-cooling.rst:69: (SEVERE/4) Unexpected section title.

^
|

so fix the .rst file so that the SEVERE build error does not happen.
Also fix another minor formatting warning (unexpected unindent).

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Zhang Rui <rui.zhang@intel.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Amit Kucheria <amit.kucheria@verdurent.com>
Cc: linux-pm@vger.kernel.org
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/712c1152-56b5-307f-b3f3-ed03a30b804a@infradead.org

Documentation/driver-api/thermal/cpu-idle-cooling.rst

@@ -65,6 +65,8 @@ We use a fixed duration of idle injection that gives an acceptable
 performance penalty and a fixed latency. Mitigation can be increased
 or decreased by modulating the duty cycle of the idle injection.
 
+::
+
      ^
      |
      |
@@ -91,6 +93,8 @@ computed.
 The governor will change the cooling device state thus the duty cycle
 and this variation will modulate the cooling effect.
 
+::
+
      ^
      |
      |
@@ -154,6 +158,7 @@ equation:
 
  P(opp)target = ((Trunning x (P(opp)running) + (Tidle x P(opp)idle)) /
 			(Trunning + Tidle)
+
   ...
 
  Tidle = Trunning x ((P(opp)running / P(opp)target) - 1)