webos.conf: Release webOS OSE v2.18.0

:Release Notes:
Set software version as webOS OSE v2.18.0

:Detailed Notes:
Set WEBOS_DISTRO_VERSION_MINOR to "18.0"

:Testing Performed:
Only build tested.

:QA Notes:
No change to image.

:Issues Addressed:
N/A

Change-Id: Id65ecf88087489392217ff59b6dd35689632141d

meta-webos/conf/distro/webos.conf

@@ -13,7 +13,7 @@ WEBOS_DISTRO_BUILD_CODENAME = "master"
 #    g - github
 
 WEBOS_DISTRO_VERSION_MAJOR = "2"
-WEBOS_DISTRO_VERSION_MINOR = "17.0"
+WEBOS_DISTRO_VERSION_MINOR = "18.0"
 WEBOS_DISTRO_VERSION_TYPE = "g"
 
 DISTRO_VERSION = "${WEBOS_DISTRO_VERSION_MAJOR}.${WEBOS_DISTRO_VERSION_MINOR}.${WEBOS_DISTRO_VERSION_TYPE}"