fix(markdown): color deprecated html attributes (#12)

* chore: add html to markdown example

* fix(markdown): color deprecated html attributes

Author: kettanaito

demo/markdown.md

@@ -14,13 +14,15 @@
 6.  Click **Reload** to reload the Code
 7.  File > Preferences > Color Theme > **Night Owl**
 
--[ ] check check 12 12
--[ ] check check 12 12
+- [ ] check check 12 12
+- [ ] check check 12 12
 
-Heading 1
-========
+# Heading 1
 
-Heading 2
---------------
+## Heading 2
 
 ### Heading 3
+
+<div align="center">
+  <img src="example.png" alt="Example image" />
+</div>

themes/codesandbox-dark.json

@@ -163,11 +163,6 @@
       "scope": ["constant"],
       "settings": { "foreground": "#7AD9FB" }
     },
-    {
-      "name": "invalid",
-      "scope": ["invalid"],
-      "settings": { "foreground": "#86897A" }
-    },
     {
       "name": "keyword",
       "scope": ["keyword"],
@@ -505,6 +500,11 @@
       "scope": ["meta.paragraph.markdown"],
       "settings": { "foreground": "#e5e5e5" }
     },
+    {
+      "name": "text.html.markdown meta.attribute",
+      "scope": ["text.html.markdown meta.attribute"],
+      "settings": { "foreground": "#CABEFF" }
+    },
     {
       "name": "entity.name.section",
       "scope": ["entity.name.section"],