Add dependabot.yml to enable dependabot beta (#930)

* Add dependabot.yml to enable dependabot beta

Dependabot version update is now in beta, see post at:
https://github.blog/2020-06-01-keep-all-your-packages-up-to-date-with-dependabot/

Once this flow has been validated, we can remove the dependabot-preview app.
We may have to check in some changes to tell dependabot not to ignore this or that package, as we've previously done with comment in the PRs raised. With a bit of luck, the bot will have the right to run builds on azure pipelines.

See also:
- https://help.github.com/en/github/administering-a-repository/enabling-and-disabling-version-updates
- https://help.github.com/en/github/administering-a-repository/customizing-dependency-updates

* let's make it daily at first

* Rename file

* Fix mess... Should have been clean rename

Co-authored-by: Jeroen Rietveld <jerietve@microsoft.com>

.github/dependabot.yml

@@ -0,0 +1,9 @@
+version: 2
+updates:
+  # Enable version updates for npm
+  - package-ecosystem: "npm"
+    # Look for `package.json` and `lock` files in the `root` directory
+    directory: "/"
+    # Check the npm registry for updates every weekday
+    schedule:
+      interval: "daily"