Docs: compiler.cfg.instructions improvements
compiler.cfg.build-stack-frame: stub docs and tests for vocab
compiler.cfg.stack-frame: stub docs and tests for vocab
compiler.cfg.linear-scan.allocation.state: sub docs and tests
compiler.cfg.linear-scan.assignment: stub docs
Docs: smallish improvements to compiler vocabs
compiler.cfg.instructions: more docs
compiler.cfg.def-use: docs
compiler.cfg.linear-scan.*: stub docs and tests
cpu.architecture: docs and some tests
compiler.codegen.gc-maps: docs and tests
Docs: more various compiler doc improvements