docs: update README.md

Author: trldvix

README.md

@@ -9,14 +9,17 @@
 
 ### This library uses undocumented YouTube API, so it's possible that it will stop working at any time. Use at your own risk.
 
+> **Note:** If you want to use this library on Android platform, refer to
+> [Android compatibility](#android-compatibility).
+
 ## 📖 Introduction
 
 Java library which allows you to retrieve subtitles/transcripts for a YouTube video.
 It supports manual and automatically generated subtitles, bulk transcript retrieval for all videos in the playlist or
 on the channel and does not use headless browser for scraping.
 Inspired by [Python library](https://github.com/jdepoix/youtube-transcript-api).
 
-## 🤖 Features
+## ☑️ Features
 
 ✅ Manual transcripts retrieval
 
@@ -146,6 +149,13 @@ TranscriptContent transcriptContent = youtubeTranscriptApi.getTranscript("videoI
 
 For bulk transcript retrieval see [Bulk Transcript Retrieval](#bulk-transcript-retrieval).
 
+## 🤖 Android compatibility
+This library uses Java 11 HttpClient for making YouTube request by default, it was done so it depends on minimal amount
+of 3rd party libraries. Since Android SDK doesn't include Java 11 HttpClient, you will have to implement
+your own `YoutubeClient` for it to work.
+
+You can check example implementation in [YoutubeClient Customization and Proxy](#youtubeclient-customization-and-proxy).
+
 ## 🔧 Detailed Usage
 
 ### Use fallback language
@@ -248,15 +258,59 @@ String formattedContent = jsonFormatter.format(transcriptContent);
 
 By default, `YoutubeTranscriptApi` uses Java 11 HttpClient for making requests to YouTube, if you want to use a
 different client or use a proxy,
-you can create your own YouTube client by implementing the `YoutubeClient` interface and passing it to
-the `TranscriptApiFactory` `createWithClient` method.
+you can create your own YouTube client by implementing the `YoutubeClient` interface.
+
+Here is example implementation using OkHttp:
 
 ```java
-// Create a new custom YoutubeClient
-YoutubeClient youtubeClient = new MyCustomYoutubeClient();
+public class OkHttpYoutubeClient implements YoutubeClient {
+
+    private final OkHttpClient client;
+
+    public OkHttpYoutubeClient(OkHttpClient client) {
+        this.client = client;
+    }
+
+    @Override
+    public String get(String url, Map<String, String> headers) throws TranscriptRetrievalException {
+        Request request = new Request.Builder()
+                .headers(Headers.of(headers))
+                .url(url)
+                .build();
+
+        return sendGetRequest(request);
+    }
 
-// Create YoutubeTranscriptApi instance with custom YouTubeClient
-YoutubeTranscriptApi youtubeTranscriptApi = TranscriptApiFactory.createWithClient(youtubeClient);
+    @Override
+    public String get(YtApiV3Endpoint endpoint, Map<String, String> params) throws TranscriptRetrievalException {
+        Request request = new Request.Builder()
+                .url(endpoint.url(params))
+                .build();
+
+        return sendGetRequest(request);
+    }
+
+    private String sendGetRequest(Request request) throws TranscriptRetrievalException {
+        try (Response response = client.newCall(request).execute()) {
+            if (response.isSuccessful()) {
+                ResponseBody body = response.body();
+                if (body == null) {
+                    throw new TranscriptRetrievalException("Response body is null");
+                }
+                return body.string();
+            }
+        } catch (IOException e) {
+            throw new TranscriptRetrievalException("Failed to retrieve data from YouTube", e);
+        }
+        throw new TranscriptRetrievalException("Failed to retrieve data from YouTube");
+    }
+}
+```
+After implementing your custom `YouTubeClient` you will need to pass it to `TranscriptApiFactory` `createWithClient` method.
+
+```java
+YoutubeClient okHttpClient = new OkHttpYoutubeClient();
+YoutubeTranscriptApi youtubeTranscriptApi = TranscriptApiFactory.createWithClient(okHttpClient);
 ```
 
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