Update iOS configuration docs (#1473)

Updating the ios configuration  section. I've problems with `duplicate file outputs` on build, when trying to install just one font on Ios. When I used pod install, this solved my problem

Co-authored-by: Joel Arvidsson <joel@oblador.se>

README.md

@@ -125,6 +125,8 @@ To use the bundled icons on iOS, follow these steps:
 
 _Note: Recompile your project after adding new fonts._
 
+_Note 2: If you're getting problems with `duplicate outputs file` for fonts on ios build, try running `cd ios && pod install` after the `react-native.config.js` configuration._
+
 ### Android Setup
 
 #### Option: With Gradle (recommended)