Add webkitResponseTimeout to ios cap doc
MODIFY
docs/en/writing-running-appium/caps.md
docs/en/writing-running-appium/caps.md
|`webviewConnectRetries`| Number of times to send connection message to remote debugger, to get webview. Default: `8` |e.g., `12`|
|`appName`| The display name of the application under test. Used to automate backgrounding the app in iOS 9+.|e.g., `UICatalog`|
|`customSSLCert`|(Sim/Emu-only) Add an SSL certificate to simulator. | e.g. <br/>`-----BEGIN CERTIFICATE-----MIIFWjCCBEKg...`<br/>`-----END CERTIFICATE-----`|
+|`webkitResponseTimeout`|(Real device only) Set the time, in ms, to wait for a response from WebKit in a Safari session. Defaults to `5000`|e.g., `10000`|
### iOS Only, using XCUITest

Add webkitResponseTimeout to ios cap doc (#8884)