Update Kotlin and add changelog for 1.2.0 (#1436)

Make guide and reference easier to find
Add MOAR badges

Co-authored-by: Vsevolod Tolstopyatov <qwwdfsad@gmail.com>
diff --git a/build.gradle b/build.gradle
index 56c8d23..17eb9b1 100644
--- a/build.gradle
+++ b/build.gradle
@@ -47,6 +47,8 @@
     repositories {
         mavenLocal()
         maven { url 'https://maven.pkg.jetbrains.space/kotlin/p/dokka/dev' }
+        // kotlin-dev with space redirector
+        maven { url "https://cache-redirector.jetbrains.com/maven.pkg.jetbrains.space/kotlin/p/kotlin/dev" }
         mavenCentral()
         gradlePluginPortal()
         // For Dokka that depends on kotlinx-html