Update README with usage example

README.md

@@ -1,23 +1,40 @@
-# function-template-go
-[![CI](https://github.com/crossplane/function-template-go/actions/workflows/ci.yml/badge.svg)](https://github.com/crossplane/function-template-go/actions/workflows/ci.yml)
-
-A template for writing a [composition function][functions] in [Go][go].
-
-To learn how to use this template:
-
-* [Follow the guide to writing a composition function in Go][function guide]
-* [Learn about how composition functions work][functions]
-* [Read the function-sdk-go package documentation][package docs]
+# function-event-filter
+[![CI](https://github.com/upbound/function-event-filter/actions/workflows/ci.yml/badge.svg)](https://github.com/upbound/function-event-filter/actions/workflows/ci.yml)
+[![Slack](https://img.shields.io/badge/slack-upbound_crossplane-purple?logo=slack)](https://crossplane.slack.com/archives/C01TRKD4623)
+
+A Crossplane function that can be used in a function pipeline to gate further
+progress within the pipeline based on supplied `Event` details.
+
+## Example usage
+```yaml
+apiVersion: ops.crossplane.io/v1alpha1
+kind: WatchOperation
+metadata:
+  name: analyze-events
+spec:
+  watch:
+    apiVersion: v1
+    kind: Event
+    namespace: crossplane-system
+  concurrencyPolicy: Forbid
+  successfulHistoryLimit: 2
+  failedHistoryLimit: 1
+  operationTemplate:
+    spec:
+      mode: Pipeline
+      pipeline:
+      # Filter events to only pass those of type "Warning".
+      - step: filter-noisy-events
+        functionRef:
+          name: function-event-filter
+        input:
+          apiVersion: filter.event.fn.upbound.io/v1alpha1
+          kind: Input
+          type: Warning
+```
 
-If you just want to jump in and get started:
 
-1. Replace `function-template-go` with your function in `go.mod`,
-   `package/crossplane.yaml`, and any Go imports. (You can also do this
-   automatically by running the `./init.sh <function-name>` script.)
-1. Update `input/v1beta1/` to reflect your desired input (and run `go generate ./...`)
-1. Add your logic to `RunFunction` in `fn.go`
-1. Add tests for your logic in `fn_test.go`
-1. Update this file, `README.md`, to be about your function!
+## Development
 
 This template uses [Go][go], [Docker][docker], and the [Crossplane CLI][cli] to
 build functions.
@@ -41,4 +58,3 @@ $ crossplane xpkg build -f package --embed-runtime-image=runtime
 [function guide]: https://docs.crossplane.io/knowledge-base/guides/write-a-composition-function-in-go
 [package docs]: https://pkg.go.dev/github.com/crossplane/function-sdk-go
 [docker]: https://www.docker.com
-[cli]: https://docs.crossplane.io/latest/cli