Update required nomad-lab version and add warning to README (#86)

* Added index url instructions to README.md

* Update required nomad-lab version to 1.3.6

README.md

@@ -8,9 +8,13 @@ This is a plugin for [NOMAD](https://nomad-lab.eu) which contains base sections
 material processing.
 
 ## Getting started
-`nomad-material-processing` can be installed from PyPI using `pip`:
+`nomad-material-processing` can be installed from PyPI using `pip`. 
+
+> [!WARNING] 
+> Unfortunately, the current plugin mechanism is not supported by the latest nomad-lab version on PyPI and therefore an index url pointing to the NOMAD Gitlab registry needs to be added.
+
 ```sh
-pip install nomad-material-processing
+pip install nomad-material-processing --index-url https://gitlab.mpcdf.mpg.de/api/v4/projects/2187/packages/pypi/simple
 ```
 
 ### Setting up your OASIS

pyproject.toml

@@ -28,7 +28,7 @@ authors = [
 ]
 license = { file = "LICENSE" }
 dependencies = [
-    "nomad-lab>=1.3.4dev",
+    "nomad-lab>=1.3.6",
 ]
 
 [project.urls]