docs: add note about TLS versions

Related: #298

Author: darrachequesne

src/site/markdown/faq.md

@@ -121,3 +121,30 @@ Sticky sessions can be enabled on AWS Application Load Balancers, which works by
 Please see [above](#how-to-deal-with-cookies) for how to deal with cookies.
 
 Reference: https://docs.aws.amazon.com/elasticloadbalancing/latest/application/sticky-sessions.html
+
+## How to force TLS v1.2 and above
+
+This library relies on the OkHttp library to create HTTP requests and WebSocket connections.
+
+Reference: https://square.github.io/okhttp/
+
+We currently depend on version `3.12.12`, which is the last version that supports Java 7+ and Android 2.3+ (API level 9+). With this version, the OkHttpClient allows `TLSv1` and `TLSv1.1` by default ([MODERN_TLS](https://square.github.io/okhttp/security/tls_configuration_history/#modern_tls-versions_1) configuration).
+
+You can overwrite it by providing your own OkHttp client:
+
+```java
+OkHttpClient okHttpClient = new OkHttpClient.Builder()
+        .connectionSpecs(Arrays.asList(
+            ConnectionSpec.RESTRICTED_TLS
+        ))
+        .readTimeout(1, TimeUnit.MINUTES) // important for HTTP long-polling
+        .build();
+
+IO.Options options = new IO.Options();
+options.callFactory = okHttpClient;
+options.webSocketFactory = okHttpClient;
+
+Socket socket = IO.socket(URI.create("https://example.com"), options);
+```
+
+Note: we will upgrade to OkHttp 4 in the next major version.

src/site/markdown/installation.md

@@ -31,3 +31,12 @@ implementation ('io.socket:socket.io-client:2.0.1') {
   exclude group: 'org.json', module: 'json'
 }
 ```
+
+## Dependency tree
+
+| `socket.io-client`                                                                                                          | `engine.io-client`                                                                                                          | `okhttp`                                                                                        |
+|-----------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------|
+| `2.0.1` ([diff](https://github.com/socketio/socket.io-client-java/compare/socket.io-client-2.0.0...socket.io-client-2.0.1)) | `2.0.0`                                                                                                                     | `3.12.12`                                                                                       |
+| `2.0.0` ([diff](https://github.com/socketio/socket.io-client-java/compare/socket.io-client-1.0.1...socket.io-client-2.0.0)) | `2.0.0` ([diff](https://github.com/socketio/engine.io-client-java/compare/engine.io-client-1.0.1...engine.io-client-2.0.0)) | `3.12.12`                                                                                       |
+| `1.0.1` ([diff](https://github.com/socketio/socket.io-client-java/compare/socket.io-client-1.0.0...socket.io-client-1.0.1)) | `1.0.1` ([diff](https://github.com/socketio/engine.io-client-java/compare/engine.io-client-1.0.0...engine.io-client-1.0.1)) | `3.12.12` ([changelog](https://square.github.io/okhttp/changelogs/changelog_3x/#version-31212)) |
+| `1.0.0`                                                                                                                     | `1.0.0`                                                                                                                     | `3.8.1`                                                                                         |