Dart VM build documentation clarification

[chi-w-ng]

We embed dart vm in a C++ application. For dart 3.6.2, We embed via a static library libdart build using
the command build.py --mode release --arch x64 libart.

For dart 3.8.0, libart is no longer recognized as a valid target.

We were adviced to try targets "libdart_jit" or "libdart_aotruntime" but these are runtimes, please refers to issue #60799.
We are unfamiliar with the build system. Where or how could we find all available build target?

[mraleph]

Lets continue discussion on the existing issue.