fix(markdown-preview-nvim): yarn istead of npm (#770)

* fix: yarn istead of npm

**Issue**

- iamcco/markdown-preview.nvim#616

* chore: fix lint tabwidth 2

* chore(lint): fix ending line of table

lua/astrocommunity/markdown-and-latex/markdown-preview-nvim/init.lua

@@ -1,5 +1,5 @@
 return {
   "iamcco/markdown-preview.nvim",
-  build = "cd app && npm install",
+  build = "cd app && yarn install",
   ft = "markdown",
 }