Extend the docs with tutorial 13
The tutorial 13 README could be converted into a tutorial in the NOMAD docs. Specifically part 3 on plugin development: [https://github.com/FAIRmat-NFDI/AreaA-Examples/tree/main/tutorial13/part3](https://github.com/FAIRmat-NFDI/AreaA-Examples/blob/main/tutorial13/part3/README.md) and part 4 on deploying an Oasis with custom plugins: [github.com/FAIRmat-NFDI/AreaA-Examples/tree/main/tutorial13/part4](https://github.com/FAIRmat-NFDI/AreaA-Examples/blob/main/tutorial13/part4/README.md) Maybe we could also include part 2 and a bit on yaml schema writing in between.
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