Implement the Codecov configuration file

It sets the default branch from "master" to "develop" and enables
partials analysis which is available through Codecov for JavaScript
sources.

GH-44

.codecov.yml

@@ -0,0 +1,19 @@
+# Copyright (C) 2018-present Arctic Ice Studio <[email protected]>
+# Copyright (C) 2018-present Sven Greb <[email protected]>
+#
+# Project:    Nord Docs
+# Repository: https://github.com/arcticicestudio/nord-docs
+# License:    MIT
+
+# Configuration for Codecov.
+#
+# References:
+# - https://docs.codecov.io/docs/codecov-yaml
+# - https://docs.codecov.io/docs/node
+
+codecov:
+  branch: develop
+
+parsers:
+  javascript:
+    enable_partials: yes