add a source code link in "Pod Sync" section

README.md

@@ -253,7 +253,7 @@ Okay, the main controller loop has finished, phew! Let's summarise: the HTTP req
 
 The kubelet is an agent that runs on every node in a Kubernetes cluster and is responsible for, among other things, managing the lifecycle of Pods. This means it handles all of the translation logic between the abstraction of a "Pod" (which is really just a Kubernetes concept) and its building blocks, containers. It also handles all of the associated logic around mounting volumes, container logging, garbage collection, and many more important things.
 
-A useful way of thinking about the kubelet is again like a controller! It queries Pods from kube-apiserver every 20 seconds (this is configurable), filtering the ones whose `NodeName` matches the name of the node the kubelet is running on. Once it has that list, it detects new additions by comparing against its own internal cache and begins to synchronise state if any discrepencies exist. Let's take a look at what that synchronization process looks like:
+A useful way of thinking about the kubelet is again like a controller! It queries Pods from kube-apiserver every 20 seconds (this is configurable), filtering the ones whose `NodeName` [matches the name](https://github.com/kubernetes/kubernetes/blob/3b66adb8bc6929e1205bcb2bc32f380c39be8381/pkg/kubelet/config/apiserver.go#L34) of the node the kubelet is running on. Once it has that list, it detects new additions by comparing against its own internal cache and begins to synchronise state if any discrepencies exist. Let's take a look at what that synchronization process looks like:
 
 1. If the pod is being created (ours is!), it [registers some startup metrics](https://github.com/kubernetes/kubernetes/blob/fc8bfe2d8929e11a898c4557f9323c482b5e8842/pkg/kubelet/kubelet.go#L1519) that is used in Prometheus for tracking pod latency.
 1. It then [generates a PodStatus](https://github.com/kubernetes/kubernetes/blob/dd9981d038012c120525c9e6df98b3beb3ef19e1/pkg/kubelet/kubelet_pods.go#L1287) object, which represents the state of a Pod's current Phase. The Phase of a Pod is a high-level summary of where the Pod is in its lifecycle. Examples include `Pending`, `Running`, `Succeeded`, `Failed` and `Unknown`. Generating this state is quite complicated, so let's dive into exactly what happens: