Fix YAML pipeline paths in docker-compose.yml

[ZanSara]

Closes #2324

Problem:
The quick demo did not validate the YAML for indexing pipelines and, when we renamed the YAML files to enable automatic validation in the IDE, we forgot to update the paths in the docker-compose* files. The YAML loading did not fail for non-existing files, and his lead to a cryptic error where it seemed that pipelines was not defined in the pipeline file.

Solution

• FIx the paths in docker-compose.yml and docker-compose-gpu.yml
• Add check for non-existing files in read_pipeline_config_from_yaml
• Modify the REST API indexing pipeline load procedure to validate the config file
• Add note about IDE autocompletion in the YAML files

[ZanSara]

@julian-risch: Apparently somebody did not wait for the CI to finish before merging their PR and now I have unrelated changed related to the evaluation in my PR. Shall we let them into this one?

[julian-risch]

@julian-risch: Apparently somebody did not wait for the CI to finish before merging their PR and now I have unrelated changed related to the evaluation in my PR. Shall we let them into this one?

Yes, let's do that. You're referring to docs/_src/api/api/evaluation.md for example, correct?

[julian-risch]

LGTM 👍