Add Read In The Contents Of A File as a Deno til

deno/read-in-the-contents-of-a-file.md

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+# Read In The Contents Of A File
+
+Deno offers some nice utilities out of the box like reading in the contents of
+a file from the filesystem. The `readTextFile` function is available on the
+`Deno` object.
+
+```typescript
+// Read a file using Deno
+const text: string = await Deno.readTextFile("./first_input.txt");
+```
+
+You use a top-level await with the function call and, assuming the file exists,
+it will read the contents in. In this case, I assign them to the `text`
+variable.
+
+For the file reading to work when the program is executed, you must use the
+`--allow-read` flag.
+
+```bash
+$ deno run --allow-read program.ts
+```
+
+[source](https://deno.land/manual@v1.14.0/examples/read_write_files)