examples: add binary payload example (#2016)

idea taken from #2004

examples/binary-reply.js

@@ -0,0 +1,32 @@
+const http = require('http')
+const fs = require('fs')
+
+const nock = require('../')
+
+const readFile = function () {
+  return fs.readFileSync(`${__dirname}/../tests/assets/reply_file_2.txt.gz`)
+}
+
+nock('http://binary.com').get('/binary').reply(200, readFile(), {
+  'content-type': 'application/octet-stream',
+  'content-length': readFile().length,
+  'content-disposition': 'attachment; filename=reply_file_2.tar.gz',
+})
+
+http.get('http://binary.com/binary', function (res) {
+  const data = []
+  res.on('data', function (chunk) {
+    // try this
+    // chunk[0] = 1;
+    // chunk[1] = 1;
+    data.push(chunk)
+  })
+  res.on('end', function () {
+    const buffer = Buffer.concat(data)
+    console.log(
+      Buffer.compare(readFile(), buffer) === 0
+        ? 'Received the file.'
+        : 'Received something else.'
+    )
+  })
+})