chore: fix mdn urls

Author: mdn-bot

css/properties/reading-flow.json

@@ -3,6 +3,7 @@
     "properties": {
       "reading-flow": {
         "__compat": {
+          "mdn_url": "https://developer.mozilla.org/docs/Web/CSS/reading-flow",
           "spec_url": "https://drafts.csswg.org/css-display-4/#reading-flow",
           "tags": [
             "web-features:reading-flow"

css/properties/reading-order.json

@@ -3,6 +3,7 @@
     "properties": {
       "reading-order": {
         "__compat": {
+          "mdn_url": "https://developer.mozilla.org/docs/Web/CSS/reading-order",
           "spec_url": "https://drafts.csswg.org/css-display-4/#propdef-reading-order",
           "support": {
             "chrome": {