Use .adoc as extension

Signed-off-by: aradermache <ansgar.radermacher@cea.fr>

getting-started.adoc

+https://gitlab.eclipse.org/eclipse/papyrus/org.eclipse.papyrus-designer/-/wikis[< Papyrus SW designer]
+
+[[getting_started]]
+== Getting started
+
+[[installation_instructions]]
+=== Installation instructions
+
+Papyrus Designer is an extension of the Papyrus modeler. In order to install it, there are three different methods.
+
+{empty}1. The easiest way (if Papyrus is not already installed) is to install the Papyrus SW designer RCP https://download.eclipse.org/modeling/mdt/papyrus/components/designer/releases/3.0.0/rcps/products/[1]. Nightly RCPs for Eclipse 2023-03 are available as well https://ci.eclipse.org/papyrus/job/papyrus-designer-2023-03/lastSuccessfulBuild/artifact/releng/org.eclipse.papyrus.designer.product/target/products/[2].
+
+{empty}2. Install Papyrus Software designer via the https://marketplace.eclipse.org/content/papyrus-software-designer[market place]].
+
+{empty}3. Open the standard Eclipse installation dialog (Help->Install New Software).
+
+Within, add either a release update site of SW designer: https://download.eclipse.org/modeling/mdt/papyrus/components/designer/releases/3.0.0/p2[Release 3.0.0], https://download.eclipse.org/modeling/mdt/papyrus/components/designer/2.1.0[Release 2.1.0] (until 2021-06) or a nightly a nightly build https://ci.eclipse.org/papyrus/job/papyrus-designer-2022-12/lastSuccessfulBuild/artifact/releng/org.eclipse.papyrus.designer.p2/target/repository/[3], https://ci.eclipse.org/papyrus/job/papyrus-designer-2023-03/lastSuccessfulBuild/artifact/releng/org.eclipse.papyrus.designer.p2/target/repository/[4].
+
+Please note that Papyrus SW designer depends on CDT (C++ code generation feature) and JDT (Java code generation) which both require a Java VM 17 in recent Eclipse version. This implies that you cannot use this installation option, if your existing Eclipse installation ships with an embedded Java VM that is older or the installed Java in your system is older. This is currently the case for Papyrus RCPs older than 2023-03.
+
+[[papyrus_vs._papyrus_sw_designer_versions]]
+==== Papyrus vs. Papyrus SW designer versions
+
+Papyrus SW Designer is an extension of Papyrus, but it is not part of the release train and released independently of Papyrus itself. Therefore, the version numbers differ.
+
+Release 3.0.0 of SW Designer is compatible with Papyrus 6.0 and 7.0 +
+Release 2.1.0 of SW Designer is compatible with Papyrus 5.0 and 6.0. +
+Release 2.0.0 of SW Designer is compatible with Papyrus 5.0 (for Eclipse version s 2021-03 and earlier)
+
+[[provided_examples]]
+=== Provided Examples
+
+A good starting point for Papyrus Designer are example models containing comments. These examples are available via File->New->Example, category "Papyrus" examples.