EVAN-6536: fix iOS/Android tutorial to work with Kotlin 1.3.21+, update minimal version in the text
EVAN-6536: fix iOS/Android tutorial to work with Kotlin 1.3.21+, update minimal version in the text

hltj/kotlin-web-site-cn,JetBrains/kotlin-web-site,hltj/kotlin-web-site-cn,JetBrains/kotlin-web-site,hltj/kotlin-web-site-cn,JetBrains/kotlin-web-site,JetBrains/kotlin-web-site,JetBrains/kotlin-web-site,hltj/kotlin-web-site-cn,hltj/kotlin-web-site-cn,hltj/kotlin-web-site-cn,JetBrains/kotlin-web-site