chore(docs): automatic generate pipeline docs

[maxgio92]

This commit adds a make target to generate documentation for pipelines. It also makes it run during the verify github workflow, alongside the generation of documentation of melange itself.

[maxgio92]

To make build package pipelines pass, the following PR is needed I think:

• https://github.com/wolfi-dev/os/pull/36623

[philroche]

Nice work. This will be very helpful