Docs: regex tag matching

This feels cursed.

docs/examples/tags/alt.log

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+./gen.sh -s alt -t unbounded_hAdX
+$ sby --dumptasks alt.sby
+$ sby --dumptags alt.sby
+known
+liveness
+unbounded
+$ sby --dumptags alt.sby unbounded_hAdX
+\w+_h[AB]d[XY]
+known
+unbounded
+unbounded_h.d.
+$ sby --dumpdefaults alt.sby
+$ sby --dumpcfg alt.sby
+[tasks]
+unbounded_h.d. : unbounded
+liveness_h.d. : liveness
+\w+_h[AB]d[XY] : known
+
+[options]
+
+[engines]
+abc pdr
+aiger suprove
+
+[script]
+
+[files]
+$ sby --dumpcfg alt.sby unbounded_hAdX
+[options]
+mode prove
+
+[engines]
+abc pdr
+
+[script]
+read -sv A.v X.v unbounded.v
+prep -top unbounded
+
+[files]
+unbounded.v
+hostA.v
+deviceX.v

docs/examples/tags/alt.sby

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+[tasks]
+unbounded_h.d. : unbounded
+liveness_h.d. : liveness
+\w+_h[AB]d[XY] : known
+
+[options]
+unbounded: mode prove
+liveness: mode live
+
+[engines]
+~liveness: abc pdr
+~unbounded: aiger suprove
+
+[script]
+--pycode-begin--
+m = re.fullmatch(r'(unbounded|liveness)_h(.)d(.)', task or '')
+if m:
+    top, h, d = m.groups()
+    output(f'read -sv {h}.v {d}.v {top}.v')
+    output(f'prep -top {top}')
+else:
+    assert task is None, f'Invalid task {task!r}'
+--pycode-end--
+
+[files]
+--pycode-begin--
+m = re.fullmatch(r'(\w+)_h(\w)d(\w)', task or '')
+if m:
+    assert 'known' in tags, f'Unknown host/device {task!r}'
+    top, h, d = m.groups()
+    sources = [
+        f"{top}.v",
+        f"host{h}.v",
+        f"device{d}.v",
+    ]
+    for source in sources:
+        output(source)
+--pycode-end--