added some missing steps

Added some missing steps on how to install and link package

docs/v2/ios.md

@@ -5,6 +5,24 @@
 * Xcode 10.0+
 * cocoapods
 
+```bash
+# Use npm
+npm install react-native-agora
+```
+or
+
+```bash
+# Use yarn
+yarn add react-native-agora
+```
+then you need to link the library
+
+```bash
+# Link the library
+react-native link react-native-agora
+```
+
+
 ```bash
 # installed ruby first then run it
 gem install cocoapods