Build and older release using with extra pjsip options

[meetme2meat]

I feel the guide / README.md to build this module a bit less informative.

I'm no experience on how to build an iOS thing but I tried to building it with extra pjsip option using vialerbuild command

The build succeeds but when use that build our react-native-pjsip we get seeing build error in react end.

Also, I found a difference that for release 3.2.0 size is around 100+ MB whereas in my case it around 40MB.

I don't know if the required step to build is only ./vialerbuid or I would need to run other commands like pod (which I have completely no knowledge)

[ChrisKontosEU]

I have not tried to use this lib in react native but you can first try running "pod update" in your terminal while being in the project's path.