update: tutorial on publishing a KMP library (JetBrains#288)

A full guide on publishing a KMP library to Maven Central, starring the [helpful Gradle plugin](https://github.com/vanniktech/gradle-maven-publish-plugin) by @vanniktech.

---
Co-authored-by: ElviraMustafina <57905309+ElviraMustafina@users.noreply.github.com>

Author: zamulla

images/publish/create_release_and_tag.png

@@ -38,7 +38,10 @@
 		<toc-element toc-title="Share data access layer" topic="multiplatform-ktor-sqldelight.md"/>
 	</toc-element>
 	<toc-element toc-title="Test your multiplatform app" topic="multiplatform-run-tests.md"/>
-	<toc-element topic="multiplatform-publish-apps.md"/>
+	<toc-element toc-title="Publish multiplatform projects">
+		<toc-element toc-title="KMP app" topic="multiplatform-publish-apps.md"/>
+		<toc-element toc-title="KMP library" topic="multiplatform-publish-libraries.md"/>
+	</toc-element>
 	<toc-element toc-title="Samples" topic="multiplatform-samples.md"/>
 	<toc-element toc-title="Compose Multiplatform UI framework">
 		<toc-element toc-title="Why Compose Multiplatform" href="https://www.jetbrains.com/lp/compose-multiplatform/"/>