chore: adding state and eventing to readme (#198)

* state and eventing readme

Signed-off-by: Kavindu Dodanduwa <kavindudodanduwa@gmail.com>

* readme update

Signed-off-by: Kavindu Dodanduwa <kavindudodanduwa@gmail.com>

* review - update description

Signed-off-by: Kavindu Dodanduwa <kavindudodanduwa@gmail.com>

---------

Signed-off-by: Kavindu Dodanduwa <kavindudodanduwa@gmail.com>

Author: Kavindu-Dodan

README.md

@@ -13,7 +13,7 @@
 [![a](https://img.shields.io/badge/slack-%40cncf%2Fopenfeature-brightgreen?style=flat&logo=slack)](https://cloud-native.slack.com/archives/C0344AANLA1)
 [![Go Report Card](https://goreportcard.com/badge/github.com/open-feature/go-sdk)](https://goreportcard.com/report/github.com/open-feature/go-sdk)
 [![codecov](https://codecov.io/gh/open-feature/go-sdk/branch/main/graph/badge.svg?token=FZ17BHNSU5)](https://codecov.io/gh/open-feature/go-sdk)
-[![v0.5.1](https://img.shields.io/static/v1?label=Specification&message=v0.5.1&color=yellow)](https://github.com/open-feature/spec/tree/v0.5.1)
+[![v0.6.0](https://img.shields.io/static/v1?label=Specification&message=v0.6.0&color=yellow)](https://github.com/open-feature/spec/tree/v0.6.0) 
 [![CII Best Practices](https://bestpractices.coreinfrastructure.org/projects/6601/badge)](https://bestpractices.coreinfrastructure.org/projects/6601)
 
 ## 👋 Hey there! Thanks for checking out the OpenFeature Go SDK
@@ -46,6 +46,7 @@ The release workflow generates an SBOM (using [cyclonedx](https://github.com/Cyc
 - easy integration and extension via [hooks](https://openfeature.dev/docs/reference/concepts/hooks)
 - bool, string, numeric, and object flag types
 - [context-aware](https://openfeature.dev/docs/reference/concepts/evaluation-context) evaluation
+- Supports [OpenFeature Events](https://openfeature.dev/specification/sections/events)
 
 ## 🚀 Usage:
 
@@ -201,6 +202,71 @@ c := openfeature.NewClient("log").WithLogger(l) // set the logger at client leve
 [logr](https://github.com/go-logr/logr) uses incremental verbosity levels (akin to named levels but in integer form).
 The SDK logs `info` at level `0` and `debug` at level `1`. Errors are always logged.
 
+### Named clients:
+
+Clients can be given a name. A name is a logical identifier which can be used to associate clients with a particular provider. 
+If a name has no associated provider, clients with that name use the global provider.
+
+```go
+import "github.com/open-feature/go-sdk/pkg/openfeature"
+
+...
+
+// Registering the default provider
+openfeature.SetProvider(NewLocalProvider())
+// Registering a named provider
+openfeature.SetNamedProvider("clientForCache", NewCachedProvider())
+
+// A Client backed by default provider
+clientWithDefault := openfeature.NewClient("")
+// A Client backed by NewCachedProvider
+clientForCache := openfeature.NewClient("clientForCache")
+```
+
+### Events:
+
+Events allow you to react to state changes in the provider or underlying flag management system, such as flag definition changes, provider readiness, or error conditions.
+Initialization events (PROVIDER_READY on success, PROVIDER_ERROR on failure) are dispatched for every provider.
+Some providers support additional events, such as PROVIDER_CONFIGURATION_CHANGED.
+
+Please refer to the documentation of the provider you're using to see what events are supported.
+
+```go
+import "github.com/open-feature/go-sdk/pkg/openfeature"
+
+...
+var readyHandlerCallback = func(details openfeature.EventDetails) {
+    // callback implementation
+}
+
+// Global event handler
+openfeature.AddHandler(openfeature.ProviderReady, &readyHandlerCallback)
+
+...
+
+var providerErrorCallback = func(details openfeature.EventDetails) {
+    // callback implementation
+}
+
+client := openfeature.NewClient("clientName")
+
+// Client event handler
+client.AddHandler(openfeature.ProviderError, &providerErrorCallback)
+```
+
+### Shutdown: 
+
+The OpenFeature API provides a close function to perform a cleanup of all registered providers.
+This should only be called when your application is in the process of shutting down.
+
+```go
+import "github.com/open-feature/go-sdk/pkg/openfeature"
+
+...
+
+openfeature.Shutdown()
+```
+
 ## ⭐️ Support the project
 
 - Give this repo a ⭐️!