fix(confg.cmake): set PROJECT_URL to slience CMake warning

fix(confg.cmake): set PROJECT_URL to slience CMake warning

CMake Warning at /xdt/sdk/sysroots/x86_64-aglsdk-linux/usr/share/
cmake-3.12/Modules/CMakeAfbTemplates/cmake/cmake.d/
02-variables.cmake:98 (message):
  No homepage url found.  Please set a PROJECT_URL cmake variable in
  your config.cmake.
Call Stack (most recent call first):
  /xdt/sdk/sysroots/x86_64-aglsdk-linux/usr/share/cmake-3.12/Modules/
  CMakeAfbTemplates/cmake/common.cmake:101 (include)
  /xdt/sdk/sysroots/x86_64-aglsdk-linux/usr/share/cmake-3.12/Modules/
  CMakeAfbTemplates.cmake:19 (include)
  conf.d/cmake/config.cmake:166 (include)
  CMakeLists.txt:21 (include)

Bug-AGL: SPEC-2804

Change-Id: Iad7cc6476d2e07629299edc1bae092a533065a46
Signed-off-by: Li Xiaoming <lixm.fnst@cn.fujitsu.com>