Port to GitHub actions & publish to Terraform registry (#39)

* Port to GitHub actions

* Fix

* Make docs terraform registry compatible

docs/resources/bitbucketserver_group.md

@@ -0,0 +1,24 @@
+# Resource: bitbucketserver_group
+
+Create a Bitbucket group.
+
+## Example Usage
+
+```hcl
+resource "bitbucketserver_group" "browncoats" {
+  name = "browncoats"
+}
+```
+
+## Argument Reference
+
+* `name` - Required. Group to create.
+* `import_if_exists` - Optional. Import groups that already exist in bitbucket into the terraform state file.
+
+## Import
+
+Import a group reference via the name.
+
+```
+terraform import bitbucketserver_group.test browncoats
+```