fix: Add f5-transportserver docs

docs/sources/f5-transportserver.md

@@ -0,0 +1,33 @@
+# F5 Networks TransportServer Source
+This tutorial describes how to configure ExternalDNS to use the F5 Networks TransportServer Source. It is meant to supplement the other provider-specific setup tutorials.
+
+The F5 Networks TransportServer CRD is part of [this](https://github.com/F5Networks/k8s-bigip-ctlr) project. See more in-depth info regarding the TransportServer CRD [here](https://github.com/F5Networks/k8s-bigip-ctlr/tree/master/docs/cis-20.x/config_examples/customResource/TransportServer).
+
+## Start with ExternalDNS with the F5 Networks TransportServer source
+
+1. Make sure that you have the `k8s-bigip-ctlr` installed in your cluster. The needed CRDs are bundled within the controller.
+
+2. In your Helm `values.yaml` add:
+```
+sources:
+  - ...
+  - f5-transportserver
+  - ...
+```
+or add it in your `Deployment` if you aren't installing `external-dns` via Helm:
+```
+args:
+- --source=f5-transportserver
+```
+
+Note that, in case you're not installing via Helm, you'll need the following in the `ClusterRole` bound to the service account of `external-dns`:
+```
+- apiGroups:
+  - cis.f5.com
+  resources:
+  - transportservers
+  verbs:
+  - get
+  - list
+  - watch
+```