DOCSP-6398: [k8s] Include copyright notices in the Kubernetes operator's docs (#150)

Author: steveren

source/third-party-licenses.txt

@@ -1,3 +1,5 @@
+:noprevnext:
+
 ====================
 Third-Party Licenses
 ====================
@@ -34,3 +36,17 @@ Apache License 2.0
    * - `k8s.io/client-go <https://godoc.org/k8s.io/client-go>`__
    * - `k8s.io/kube-openapi <https://godoc.org/k8s.io/kube-openapi>`__
 
+Go-FlowRate
+-----------
+
+- `MIT License <https://github.com/mxk/go-flowrate/blob/master/LICENSE>`__
+
+Go-difflib
+----------
+
+- `3-Clause BSD License <https://github.com/pmezard/go-difflib/blob/master/LICENSE>`__
+
+Go-diff
+-------
+
+- `3-Clause BSD License <https://github.com/sergi/go-diff/blob/master/LICENSE>`__