add launch.json for xdebug

.vscode/launch.json

+{
+   "version": "0.2.0",
+   "configurations": [
+   {
+      "name": "Listen for XDebug",
+      "type": "php",
+      "request": "launch",
+      "pathMappings": {
+         "/var/www/html/tt-rss": "${workspaceRoot}",
+      },
+      "port": 9000
+  }]
+}
\ No newline at end of file