Create README and examples directory (#324)

Start adding more examples to repo

examples/README.md

@@ -0,0 +1,14 @@
+MongoDB Atlas Provider Examples
+
+This directory contains various examples of using the MongoDB Atlas Provider.  Each example has a README containing more details on what the example does and any details required to configure it.
+
+To run any example, clone the repository, edit any required variales and run terraform plan/apply within the example's own directory.
+
+For example:
+
+$ git clone https://github.com/mongodb/terraform-provider-mongodbatlas
+$ cd terraform-provider-mongodbatlas/examples/example1
+Edit variables as needed
+$ terraform plan
+$ terraform apply
+...