[Gys]

Accessing the documentation is more like a one time thing. I could always copy it somewhere else for later reference.

[antpls]

Like any file that you would hide with GitRoyalty, you could always share the full repo once you have access to it (probably illegally)

I believe documentation would become outdated sooner than build scripts with new releases, and would require effort to maintain (more than build scripts), which would better justify to pay.

Anyway, the idea of GitRoyalty seems not to make technically impossible to share the payed content, but rather to propose a way for honest people to remunerate honest developers and library maintainers.