README.md in unleash-5.0.3 vs README.md in unleash-5.0.4

@@ -22,11 +22,11 @@
 ## Installation
 
 Add this line to your application's Gemfile:
 
 ```ruby
-gem 'unleash', '~> 5.0.0'
+gem 'unleash', '~> 5.0.4'
 ```
 
 And then execute:
 
     $ bundle
@@ -42,13 +42,13 @@
 - `app_name` with the name of the runninng application.
 - `custom_http_headers` with `{'Authorization': '<API token>'}` when using Unleash v4.0.0 and later.
 
 Please substitute the example `'https://unleash.herokuapp.com/api'` for the url of your own instance.
 
-### instance_id
+It is **highly recommended** to configure:
+- `instance_id` parameter with a unique identifier for the running instance.
 
-As of version 6.0.0, `instance_id` is now an automatically generated read-only property.
 
 ```ruby
 Unleash.configure do |config|
   config.app_name            = 'my_ruby_app'
   config.url                 = 'https://unleash.herokuapp.com/api'
@@ -82,10 +82,11 @@
 
 Argument | Description | Required? |  Type |  Default Value|
 ---------|-------------|-----------|-------|---------------|
 `url`      | Unleash server URL. | Y | String | N/A |
 `app_name` | Name of your program. | Y | String | N/A |
+`instance_id` | Identifier for the running instance of program. Important so you can trace back to where metrics are being collected from. **Highly recommended be be set.** | N | String | random UUID |
 `environment` | Unleash context option. Could be for example `prod` or `dev`. Not yet in use. **Not** the same as the SDK's [Unleash environment](https://docs.getunleash.io/reference/environments). | N | String | `default` |
 `project_name` | Name of the project to retrieve features from. If not set, all feature flags will be retrieved. | N | String | nil |
 `refresh_interval` | How often the unleash client should check with the server for configuration changes. | N | Integer |  15 |
 `metrics_interval` | How often the unleash client should send metrics to server. | N | Integer | 60 |
 `disable_client` | Disables all communication with the Unleash server, effectively taking it *offline*. If set, `is_enabled?` will always answer with the `default_value` and configuration validation is skipped. Will also forcefully set `disable_metrics` to `true`. Defeats the entire purpose of using unleash, except when running tests. | N | Boolean | `false` |
@@ -139,18 +140,23 @@
 
 ```ruby
 Unleash.configure do |config|
   config.app_name = Rails.application.class.parent.to_s
   config.url      = 'https://unleash.herokuapp.com/api'
+  # config.instance_id = "#{Socket.gethostname}"
   config.logger   = Rails.logger
 end
 
 UNLEASH = Unleash::Client.new
 
 # Or if preferred:
 # Rails.configuration.unleash = Unleash::Client.new
 ```
+For `config.instance_id` use a string with a unique identification for the running instance.
+For example: it could be the hostname, if you only run one App per host.
+Or the docker container id, if you are running in docker.
+If it is not set the client will generate an unique UUID for each execution.
 
 To have it available in the `rails console` command as well, also add to the file above:
 ```ruby
 Rails.application.console do
   UNLEASH = Unleash::Client.new
@@ -240,9 +246,10 @@
 ```ruby
 PhusionPassenger.on_event(:starting_worker_process) do |forked|
   if forked
     Unleash.configure do |config|
       config.app_name    = Rails.application.class.parent.to_s
+      # config.instance_id = "#{Socket.gethostname}"
       config.logger      = Rails.logger
       config.url                 = 'https://unleash.herokuapp.com/api'
       config.custom_http_headers = {'Authorization': '<API token>'}
     end