[MAINT] run check links on master

[Remi-Gau]

No description provided.

[yibeichan]

The following are failed links (fix them later as we fix the doc):

FILE: ./docs/index.md
./30_schema → Status: 400 [Error: ENOENT: no such file or directory, access '/github/workspace/docs/30_schema']
(I think it's moved to ./docs/30_schema)

FILE: ./docs/30_schema.md
[✖] https://github.com/ReproNim/reproschema/examples → Status: 404
[✖] https://github.com/ReproNim/reproschema/terms → Status: 404

FILE: ./docs/52_create_new_activity.md
[✖] https://doi.org/10.1080/1357650X.2013.783045 → Status: 403

FILE: ./docs/51_create_new_protocol.md
[✖] https://jsonlint.com/ → Status: 400