docs/esp8266/tutorial/intro: Sphinx requires blank lines around literal blocks.

At least, Sphinx 1.3.6.

docs/esp8266/tutorial/intro.rst

@@ -165,7 +165,9 @@ after it, here are troubleshooting recommendations:
 
 * If lower baud rate didn't help, you may want to try older version of
   esptool.py, which had a different programming algorithm::
+
     pip install esptool==1.0.1
+
   This version doesn't support ``--flash_size=detect`` option, so you will
   need to specify FlashROM size explicitly (in megabits). It also requires
   Python 2.7, so you may need to use ``pip2`` instead of ``pip`` in the
@@ -180,8 +182,10 @@ after it, here are troubleshooting recommendations:
 * Additionally, you can check the firmware integrity from a MicroPython REPL
   prompt (assuming you were able to flash it and ``--verify`` option doesn't
   report errors)::
+
     import esp
     esp.check_fw()
+
   If the last output value is True, the firmware is OK. Otherwise, it's
   corrupted and need to be reflashed correctly.