Skip doc generation for nonbootstrapped library projects

[tanishiking]

Running sbt publishLocal on the root project (scala3-nonbootstrapped) is slower than necessary because it generates scaladoc for scala3-library-nonbootstrapped while other nonbootstrapped projects like scala3-compiler and tasty-core disables doc generation.

IIUC, doc jars for nonbootstrapped projects are not used, these artifacts are only published locally for bootstrapping (and local development), and the bootstrapped projects reference packageBin outputs and don't care about packageDoc.

Compiler version

HEAD

Minimized example

$ sbt publishLocal

Output

It processes docs/_docs/reference/ md files.

Expectation

publishLocal on nonbootstrapped projects shouldn't trigger doc generation.