Renamed source directory, changed dockerfile for running docker image according to the official documentation

composer.json

@@ -28,16 +28,16 @@
   ],
   "extra": {
     "installer-paths": {
-      "html/wp-content/plugins/{$name}/": [
+      "wordpress/wp-content/plugins/{$name}/": [
         "type:wordpress-plugin"
       ],
-      "html/wp-content/themes/{$name}/": [
+      "wordpress/wp-content/themes/{$name}/": [
         "type:wordpress-theme"
       ]
     }
   },
   "config": {
-    "vendor-dir": "html/wp-content/vendor",
+    "vendor-dir": "wordpress/wp-content/vendor",
     "allow-plugins": {
       "composer/installers": true
     }