docs: Fixed some invalid links on the webpage.

README.md

@@ -83,7 +83,7 @@ It also provides (Java) tools for usage inside an application:
 ## Getting started
 
 Depending on the programming language, the usage will differ, therefore please go to the
-[Getting Started](https://plc4x.apache.org/users/gettingstarted.html) on the PLC4X website to look up
+[Getting Started](https://plc4x.apache.org/users/getting-started/plc4j.html) on the PLC4X website to look up
 the language of choice.
 
 ### Java

src/site/asciidoc/index.adoc

@@ -40,7 +40,7 @@
                         industrial
                         programmable logic controllers (PLCs) using a variety of protocols but with a shared API.</div>
                     <div class="center text-center">
-                    <a href="users/gettingstarted.html"
+                    <a href="users/getting-started/plc4j.html"
                        class="plc4x-button plc4x-button-large plc4x-button-primary text-center"><i
                             class="fas fa-rocket"></i> Get started
                     </a>