[DOCS] Updates README, client docs, yard in gitignore

Author: picandocodigo

.gitignore

@@ -4,4 +4,6 @@ Gemfile.lock
 .DS_Store
 tmp
 *.log
-.env
+.env
+doc
+.yardoc

README.md

@@ -89,12 +89,9 @@ The parameters are:
 | `tracer`           | `Logger`  | An instance of a Logger-compatible object to use as a tracer.                                                                      |
 | `serializer_class` | `Object`  | A specific serializer class to use to serialize JSON.                                                                              |
 | `headers`          | `Hash`    | Custom HTTP Request Headers                                                                                                        |
-
-
-
 ### Using the API
 
-See [APIs](https://github.com/elastic/elasticsearch-serverless-ruby/blob/main/docs/apis.md) for the full list of available endpoints.
+See [APIs](https://github.com/elastic/elasticsearch-serverless-ruby/blob/main/docs/apis.md) for the full list of available endpoints. Check [rubydoc](https://rubydoc.info/gems/elasticsearch-serverless/) for the API reference, or run `yardoc` in the root of the project if you've checked out the code. The API reference documentation will be generated in the `doc` folder.
 
 Once you've instantiated a client with your API key and Elasticsearch endpoint, you can start ingesting documents into Elasticsearch Service. You can use the **Bulk API** for this. This API allows you to index, update and delete several documents in one request. You call the `bulk` API on the client with a body parameter, an Array of hashes that define the action and a document. Here's an example of indexing some classic books into the `books` index:
 

lib/elasticsearch-serverless.rb

@@ -27,9 +27,9 @@ class Client
 
     # Initializes an Elasticsearch Serverless Client
     #
-    # @param :api_key [String] Base64 String, format used to authenticate with Elasticsearch
-    # @param :url [String] Elasticsearch endpoint
-    # @param :arguments [Hash] Other optional arguments.
+    # @param [String] api_key Base64 String, format used to authenticate with Elasticsearch
+    # @param [String] url Elasticsearch endpoint
+    # @param [Hash] arguments Other optional arguments.
     # @option arguments [Symbol] :adapter A specific adapter for Faraday (e.g. `:patron`)
     # @option arguments [Boolean] :log Use the default logger (disabled by default)
     # @option arguments [Object] :logger An instance of a Logger-compatible object