Update architecture doc and diagram

Author: Kate Osborn

docs/architecture.md

@@ -98,27 +98,33 @@ parentheses. To enhance readability, the suffix "process" has been omitted from
 
 1. (HTTPS) *NKG* reads the *Kubernetes API* to get the latest versions of the resources in the cluster and writes to the
 API to update the handled resources' statuses and emit events.
-2. (File I/O) *NKG* generates NGINX *configuration* based on the cluster resources and writes them as `.conf` files to
-the mounted `nginx` volume, located at `/etc/nginx`. It also writes *TLS certificates* and *keys*
-from [TLS Secrets][secrets] referenced in the accepted Gateway resource to the volume at the
-path `/etc/nginx/secrets`.
+2. (File I/O)
+   - Write: *NKG* generates NGINX *configuration* based on the cluster resources and writes them as `.conf` files to the
+     mounted `nginx-conf` volume, located at `/etc/nginx/conf.d`. It also writes *TLS certificates* and *keys*
+     from [TLS Secrets][secrets] referenced in the accepted Gateway resource to the `nginx-secrets` volume at the
+     path `/etc/nginx/secrets`.
+   - Read: *NKG* reads the PID file `nginx.pid` from the `nginx-var-run` volume, located at `/var/run/nginx`. *NKG*
+     extracts the PID of the nginx process from this file in order to send reload signals to *NGINX master*.
 3. (File I/O) *NKG* writes logs to its *stdout* and *stderr*, which are collected by the container runtime.
 4. (Signal) To reload NGINX, *NKG* sends the [reload signal][reload] to the **NGINX master**.
-5. (File I/O) The *NGINX master* reads *configuration files*  and the *TLS cert and keys* referenced in the
-configuration when it starts or during a reload. These files, certificates, and keys are stored in the `nginx` volume
-that is mounted to both the `nginx-gateway` and `nginx` containers.
-6. (File I/O): The *NGINX master* writes to the auxiliary Unix sockets folder, which is mounted to the `nginx`
-container as the `var-lib-nginx` volume. The mounted path for this volume is `/var/lib/nginx`.
+5. (File I/O)
+   - Write: The *NGINX master* writes its PID to the `nginx.pid` file stored in the `nginx-var-run` volume.
+   - Read: The *NGINX master* reads *configuration files*  and the *TLS cert and keys* referenced in the configuration when
+     it starts or during a reload. These files, certificates, and keys are stored in the `nginx-conf` and `nginx-secrets`
+     volumes that are mounted to both the `nginx-gateway` and `nginx` containers.
+6. (File I/O)
+   - Write: The *NGINX master* writes to the auxiliary Unix sockets folder, which is located in the `/var/lib/nginx`
+     directory.
+   - Read: The *NGINX master* reads the `nginx.conf` file from the `/etc/nginx` directory. This [file][conf-file] contains
+     the global and http configuration settings for NGINX. In addition, *NGINX master*
+     reads the NJS modules referenced in the configuration when it starts or during a reload. NJS modules are stored in
+     the `/usr/lib/nginx/modules` directory.
 7. (File I/O) The *NGINX master* sends logs to its *stdout* and *stderr*, which are collected by the container runtime.
-8. (File I/O): The *NGINX master* reads the NJS modules referenced in the configuration when it starts or during a
-reload. NJS modules are stored in the `njs-modules` volume that is mounted to the `nginx` container.
-9. (File I/O) An *NGINX worker* writes logs to its *stdout* and *stderr*, which are collected by the container runtime.
-10. (File I/O): The *NGINX master* reads the `nginx.conf` file from the mounted `nginx-conf` volume.
-This [file][conf-file] contains the global and http configuration settings for NGINX.
-11. (Signal) The *NGINX master* controls the [lifecycle of *NGINX workers*][lifecycle] it creates workers with the new
+8. (File I/O) An *NGINX worker* writes logs to its *stdout* and *stderr*, which are collected by the container runtime.
+9. (Signal) The *NGINX master* controls the [lifecycle of *NGINX workers*][lifecycle] it creates workers with the new
 configuration and shutdowns workers with the old configuration.
-12. (HTTP,HTTPS) A *client* sends traffic to and receives traffic from any of the *NGINX workers* on ports 80 and 443.
-13. (HTTP,HTTPS) An *NGINX worker* sends traffic to and receives traffic from the *backends*.
+10. (HTTP,HTTPS) A *client* sends traffic to and receives traffic from any of the *NGINX workers* on ports 80 and 443.
+11. (HTTP,HTTPS) An *NGINX worker* sends traffic to and receives traffic from the *backends*.
 
 [controller]: https://kubernetes.io/docs/concepts/architecture/controller/
 
@@ -130,6 +136,6 @@ configuration and shutdowns workers with the old configuration.
 
 [lifecycle]: https://nginx.org/en/docs/control.html#reconfiguration
 
-[conf-file]: https://github.com/nginxinc/nginx-kubernetes-gateway/blob/main/deploy/manifests/nginx-conf.yaml
+[conf-file]: https://github.com/nginxinc/nginx-kubernetes-gateway/blob/main/internal/mode/static/nginx/conf/nginx.conf
 
 [share]: https://kubernetes.io/docs/tasks/configure-pod-container/share-process-namespace/