add settings.json so other people know how to configure VSCode

.vscode/settings.json

@@ -0,0 +1,5 @@
+{
+    "pth_gzdoom": "C:\\Games\\Doom\\Engines\\GZDoom\\gzdoom.exe",
+    "pth_chex3": "C:\\Games\\Doom\\IWADs\\chex3.wad",
+    "pth_slade": "C:\\Games\\Doom\\Modding\\SLADE\\SLADE.exe"
+}