Add overview of experimental features in Roadmap (#667)

Closes #88

Author: MakisH

content/docs/couple-your-code/advanced/couple-your-code-moving-or-changing-meshes.md

@@ -56,10 +56,11 @@ Note that inactive nodes can lead to numerical instabilities in some acceleratio
 
 {% version 3.2.0 %} This feature is new in preCICE version 3.2.0. {% endversion %}
 
-{% important %}
+{% experimental %}
 This feature is in active development and not yet feature-complete.
 If you are missing features, please check [the GitHub project](https://github.com/orgs/precice/projects/20) and comment on the issues to help us prioritize.
-{% endimportant %}
+Enable it using `<precice-configuration experimental="true">` and do not consider the configuration to be stable yet.
+{% endexperimental %}
 
 **Goal** of the remeshing support in preCICE to allow resetting meshes at runtime.
 

content/docs/couple-your-code/step-by-step/couple-your-code-gradient-data.md

@@ -9,6 +9,11 @@ summary: "So far, our mesh contains only data. This is sufficient for most of th
 This feature is available since version 2.4.0.
 {% endversion %}
 
+{% experimental %}
+This is an experimental feature.
+Enable it using `<precice-configuration experimental="true">` and do not consider the configuration to be stable yet.
+{% endexperimental %}
+
 When using `nearest-neighbor-gradient` mapping, we require coupling data and additional gradient data. We have seen in [Step 3](couple-your-code-mesh-and-data-access.html) how to write data to the mesh.
 Now, we will learn how to write gradient data to the mesh. For this purpose, we use the following API method:
 <ul id="apiTabs" class="nav nav-tabs">
@@ -126,10 +131,6 @@ while not simulation_done():
 </div>
 </div>
 
-{% experimental %}
-This is an experimental feature.
-{% endexperimental %}
-
 {% version 2.4.0 %}
 For preCICE versions lower than 2.5.0, you need to set the flag `gradient="on"` in the configuration file, whenever you require to write gradient data. An exemplary xml configuration file is given below. Starting from preCICE version 2.5.0, the gradient requirement is automatically deduced (based on the selected mapping) and can be queried in the code, as usual. Hence, the `gradient="on"` flag must not be set in the configuration file.
 {% endversion %}

content/docs/fundamentals/fundamentals-roadmap.md

@@ -13,11 +13,19 @@ In this page, you can find information about features that we plan to introduce
 If you are looking for library features introduced already in the past, have a look at our [Changelog](https://github.com/precice/precice/blob/develop/CHANGELOG.md).
 For most recent developments waiting for the next release, have a look at the [unreleased changes](#changelog).
 
+## Experimental
+
+The following features have recently been released, but are still experimental,
+meaning that the respective API or configuration might change in a minor release:
+
+- [Dynamic coupling meshes](couple-your-code-moving-or-changing-meshes.html) - Since v3.2.0 ([GitHub project](https://github.com/orgs/precice/projects/20/views/1))
+- [Just-in-time data mapping](couple-your-code-just-in-time-mapping.html), e.g., for particle codes - Since v3.2.0
+- [Geometric multi-scale data mapping](configuration-mapping.html#geometric-multiscale-mapping), e.g. for 3D-1D coupled problems - Since v3.0.0 ([GitHub project](https://github.com/orgs/precice/projects/14))
+- [Gradient data](couple-your-code-gradient-data.html) - Since v2.4.0
+
 ## In active development
 
 - [GPU support for partition-of-unity radial-basis-function data mapping](https://github.com/precice/precice/pull/2346)
-- [Dynamic coupling meshes](https://github.com/orgs/precice/projects/20/views/1)
-- [Geometric multi-scale data mapping](https://github.com/orgs/precice/projects/14), e.g. for 3D-1D and 3D-2D coupled problems
 - [Extendable and modular system tests](https://github.com/orgs/precice/projects/12)
 - [Volume coupling for OpenFOAM](https://github.com/orgs/precice/projects/9)
 - [Standardization of adapter and tooling configurations](https://github.com/precice/preeco-orga/issues/18)