[examples/data-literate][m]: factor our a working markdown+CSV (data literate) example from site (where we already had a demo).

* removed a few extraneous things
* added the README.md with some instructions

examples/data-literate/lib/mdxUtils.js

@@ -0,0 +1,23 @@
+import fs from 'fs'
+import glob from 'glob'
+import path from 'path'
+
+// POSTS_PATH is useful when you want to get the path to a specific file
+export const POSTS_PATH = path.join(process.cwd(), 'content')
+
+const walkSync = (dir, filelist = []) => {
+  fs.readdirSync(dir).forEach(file => {
+
+    filelist = fs.statSync(path.join(dir, file)).isDirectory()
+      ? walkSync(path.join(dir, file), filelist)
+      : filelist.concat(path.join(dir, file))
+
+  })
+  return filelist
+}
+
+// postFilePaths is the list of all mdx files inside the POSTS_PATH directory
+export const postFilePaths = walkSync(POSTS_PATH)
+  .map((file) => { return file.slice(POSTS_PATH.length) })
+  // Only include md(x) files
+  .filter((path) => /\.mdx?$/.test(path))