test(pymarkdown): enable inline HTML check

Blocking issue fixed in v0.9.1.

Author: scop

.pymarkdown.json

@@ -5,8 +5,7 @@
             "enabled": false
         },
         "no-inline-html": {
-            "//": "https://github.com/jackdewinter/pymarkdown/issues/22",
-            "enabled": false,
+            "//": "!-- for issue template, kbd for README and in general",
             "allowed_elements": "!--,kbd"
         },
         "ul-indent": {