Add documentation of JS DCE devMode
Add documentation of JS DCE devMode

Issue: https://youtrack.jetbrains.com/issue/KT-22318
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,JetBrains/kotlin-web-site,hltj/kotlin-web-site-cn,JetBrains/kotlin-web-site,JetBrains/kotlin-web-site,hltj/kotlin-web-site-cn,meilalina/kotlin-web-site,hltj/kotlin-web-site-cn,meilalina/kotlin-web-site,meilalina/kotlin-web-site,meilalina/kotlin-web-site