update: rewrite of ksp-quickstart.md

[[KEDOC-100](https://youtrack.jetbrains.com/issue/KEDOC-100/Update-the-KSP-quickstart)]

New quickstart for KSP based on a new [example](https://github.com/google/ksp/tree/main/examples/hello-world) in the KSP repository.

Author: budindepunk

docs/images/ksp/ksp-new-module.png

@@ -341,7 +341,7 @@
         </toc-element>
         <toc-element toc-title="Kotlin Symbol Processing API">
             <toc-element toc-title="KSP overview" topic="ksp-overview.md"/>
-            <toc-element toc-title="Quickstart" topic="ksp-quickstart.md"/>
+            <toc-element toc-title="Getting started" topic="ksp-quickstart.md"/>
             <toc-element topic="ksp-why-ksp.md"/>
             <toc-element toc-title="Examples" topic="ksp-examples.md"/>
             <toc-element topic="ksp-additional-details.md"/>