chore: remove the vim-markdown language (#67)

This is only used for the viml injection in markdown code blocks.
However, no language is needed for this, only the scope name. All
defined languages show up in the VSCode language selector.

Author: remcohaszing

package.json

@@ -75,7 +75,6 @@
         "path": "./syntaxes/vroom.tmLanguage.json"
       },
       {
-        "language": "vim-markdown",
         "scopeName": "markdown.vim.codeblock",
         "path": "./syntaxes/codeblock.json",
         "injectTo": [
@@ -130,9 +129,6 @@
         ],
         "configuration": "./syntaxes/snippet.language-configuration.json"
       },
-      {
-        "id": "vim-markdown"
-      },
       {
         "id": "vroom",
         "aliases": [
@@ -149,7 +145,6 @@
     "onLanguage:viml",
     "onLanguage:vim-help",
     "onLanguage:vim-snippet",
-    "onLanguage:vim-markdown",
     "onLanguage:vroom",
     "workspaceContains:**/.*txt"
   ],