Added information about Global Card to README
Added information about Global Card to README

VirgilSecurity/virgil-sdk-keys-ios,VirgilSecurity/virgil-sdk-keys-ios,VirgilSecurity/virgil-sdk-keys-x,VirgilSecurity/virgil-sdk-keys-ios,VirgilSecurity/virgil-sdk-keys-ios,VirgilSecurity/virgil-sdk-keys-x,VirgilSecurity/virgil-sdk-keys-x,VirgilSecurity/virgil-sdk-keys-x