fix: improve the navigation to the KMP portal (#4849)

Author: koshachy

docs/kr.tree

@@ -239,6 +239,7 @@
 			<toc-element topic="custom-script-deps-tutorial.md"/>
 		</toc-element>
 	</toc-element>
+	<toc-element href="https://www.jetbrains.com/help/kotlin-multiplatform-dev/get-started.html" toc-title="Develop with Kotlin Multiplatform"/>
 	<toc-element toc-title="Standard library">
 		<toc-element toc-title="Collections">
 			<toc-element toc-title="Overview" topic="collections-overview.md"/>