Add markdown preview, update rust.vim

sources_non_forked/markdown-preview.nvim/tsconfig.json

@@ -0,0 +1,26 @@
+{
+  "compileOnSave": true,
+  "compilerOptions": {
+    "resolveJsonModule": true,
+    "composite": true,
+    "target": "es2015",
+    "module": "commonjs",
+    "moduleResolution": "node",
+    "esModuleInterop": true,
+    "lib": [
+      "dom",
+      "esnext"
+    ],
+    "baseUrl": ".",
+    "outDir": "./app/lib",
+    "rootDir": "./src",
+    "importHelpers": true,
+    "allowSyntheticDefaultImports": true
+  },
+  "include": [
+    "./src"
+  ],
+  "exclude": [
+    "./lib"
+  ]
+}