Reduce contextual use of "NGF" three letter acronym (#1516)

For conciseness, "ngf" is often used as part of the naming conventions
for processes, image names and other artefacts. It should be avoided in
documentation when referring to the actual software, which this commit
addresses in a handful of identified instances.

site/content/overview/gateway-api-compatibility.md

@@ -107,10 +107,10 @@ See the [static-mode]({{< relref "/reference/cli-help.md#static-mode">}}) comman
     - `Accepted/False/Invalid`
     - `Accepted/False/UnsupportedValue`: Custom reason for when a value of a field in a Gateway is invalid or not supported.
     - `Accepted/False/GatewayConflict`: Custom reason for when the Gateway is ignored due to a conflicting Gateway.
-          NGF only supports a single Gateway.
+          NGINX Gateway Fabric only supports a single Gateway.
     - `Programmed/True/Programmed`
     - `Programmed/False/Invalid`
-    - `Programmed/False/GatewayConflict`: Custom reason for when the Gateway is ignored due to a conflicting Gateway. NGF only supports a single Gateway.
+    - `Programmed/False/GatewayConflict`: Custom reason for when the Gateway is ignored due to a conflicting Gateway. NGINX Gateway Fabric only supports a single Gateway.
   - `listeners`
     - `name`: Supported.
     - `supportedKinds`: Supported.
@@ -121,7 +121,7 @@ See the [static-mode]({{< relref "/reference/cli-help.md#static-mode">}}) comman
       - `Accepted/False/InvalidCertificateRef`
       - `Accepted/False/ProtocolConflict`
       - `Accepted/False/UnsupportedValue`: Custom reason for when a value of a field in a Listener is invalid or not supported.
-      - `Accepted/False/GatewayConflict`: Custom reason for when the Gateway is ignored due to a conflicting Gateway. NGF only supports a single Gateway.
+      - `Accepted/False/GatewayConflict`: Custom reason for when the Gateway is ignored due to a conflicting Gateway. NGINX Gateway Fabric only supports a single Gateway.
       - `Programmed/True/Programmed`
       - `Programmed/False/Invalid`
       - `ResolvedRefs/True/ResolvedRefs`

site/content/overview/gateway-architecture.md

@@ -60,7 +60,7 @@ This configuration happens in two stages:
 1. NGINX configuration files are written to the NGINX configuration volume shared by the `nginx-gateway` and `nginx` containers.
 1. The control plane reloads the NGINX process.
 
-This is possible because the two containers [share a process namespace](https://kubernetes.io/docs/tasks/configure-pod-container/share-process-namespace/), allowing the NGF process to send signals to the NGINX main process.
+This is possible because the two containers [share a process namespace](https://kubernetes.io/docs/tasks/configure-pod-container/share-process-namespace/), allowing the NGINX Gateway Fabric process to send signals to the NGINX main process.
 
 The following diagram represents the connections, relationships and interactions between process with the `nginx` and `nginx-gateway` containers, as well as external processes/entities.
 
@@ -71,7 +71,7 @@ The following list describes the connections, preceeded by their types in parent
 1. (HTTPS)
    - Read: _NGF_ reads the _Kubernetes API_ to get the latest versions of the resources in the cluster.
    - Write: _NGF_ writes to the _Kubernetes API_ to update the handled resources' statuses and emit events. If there's more than one replica of _NGF_ and [leader election](https://github.com/nginxinc/nginx-gateway-fabric/tree/main/deploy/helm-chart#configuration) is enabled, only the _NGF_ pod that is leading will write statuses to the _Kubernetes API_.
-1. (HTTP, HTTPS) _Prometheus_ fetches the `controller-runtime` and NGINX metrics via an HTTP endpoint that _NGF_ exposes (`:9113/metrics` by default). Prometheus is **not** required by NGF, and its endpoint can be turned off.
+1. (HTTP, HTTPS) _Prometheus_ fetches the `controller-runtime` and NGINX metrics via an HTTP endpoint that _NGF_ exposes (`:9113/metrics` by default). Prometheus is **not** required by NGINX Gateway Fabric, and its endpoint can be turned off.
 1. (File I/O)
    - Write: _NGF_ 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](https://kubernetes.io/docs/concepts/configuration/secret/#tls-secrets) referenced in the accepted Gateway resource to the `nginx-secrets` volume at the path `/etc/nginx/secrets`.
    - Read: _NGF_ reads the PID file `nginx.pid` from the `nginx-run` volume, located at `/var/run/nginx`. _NGF_ extracts the PID of the nginx process from this file in order to send reload signals to _NGINX master_.