Suricata

Each detection keyword registers an documentation URL, or should do so. This happens in the per keyword *Register function.

To check:

$ suricata --list-keywords=all
...
base64_decode:
    Description: Decodes base64 encoded data.
    Features: none
    Documentation: https://suricata.readthedocs.io/en/latest/rules/payload-keywords.html#base64-decode
...

For each keyword where an url is missing, add it. For each url that is somehow wrong, fix it.

For each url that does not lead to actually written documentation, open a feature ticket.