docs: add SPEC.md, the first written specification of zc

Reference for lexing, types, expressions (full precedence table),
statements, declarations, the ownership analyzer and its messages,
compile-time execution and the runtime contract, with appendices for
the zc0 subset and for doc/implementation disagreements and bugs found
while checking the rules against build/bin/zy. Pointers added to
README.md and ONBOARD.md.

1 files changed, 1 insertions, 1 deletions

diff --git a/README.md b/README.md
index 2752600..322d252 100644
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 a small stack cpu began as a C89 code golf entry and became a self-hosting runtime. a native core runs vm code with an arm64 jit, through llvm on supported builds, or in the interpreter. the genome contains a compiler for zc, a C-like language with forth influences. the compiler resides in vm memory alongside the program; code can call its functions, modify its tables, add syntax, and compile new code at runtime. heap objects carry an ownership tag (u, m or d) checked by a static analyzer, with deterministic frees at scope ends and a mark-sweep collector underneath. types are a compiler primitive, with structs, generics, reflection and an optional typechecker. programs can install up to 512 custom opcodes (virtual enhancements), which the jits inline as native code. code marked `o3` bypasses the stack machine: the core compiles the region as a unit and keeps its variables in registers.
 
-this folder has the latest code. `docs/LEARN.md` is a tour of the language. `docs/history/` is the scrapbook: notes for every stage, plus frozen code from the stages that still have it, archived as `docs/history/code-snapshots.tar.gz`.
+this folder has the latest code. `docs/SPEC.md` is the language reference, and `docs/LEARN.md` is a tour of the language. `docs/history/` is the scrapbook: notes for every stage, plus frozen code from the stages that still have it, archived as `docs/history/code-snapshots.tar.gz`.
 
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