Added reference to SDK 2.4.2

code/platformio.ini

@@ -12,10 +12,12 @@ data_dir = espurna/data
 #   platformIO 1.5.0 = arduino core 2.3.0
 #   platformIO 1.6.0 = arduino core 2.4.0
 #   platformIO 1.7.3 = arduino core 2.4.1
+#   platformIO 1.8.0 = arduino core 2.4.2
 # ------------------------------------------------------------------------------
 platform_150 = espressif8266@1.5.0
 platform_160 = espressif8266@1.6.0
 platform_173 = espressif8266@1.7.3
+platform_180 = espressif8266@1.8.0
 platform = ${common.platform_150}
 
 # ------------------------------------------------------------------------------