Add bin description to README
# tree-sitter-hack
[Hack](https://hacklang.org/) grammar for [tree-sitter](https://github.com/tree-sitter/tree-sitter).
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+# Workflow
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+**`bin/generate-parser`**
+
+Wrapper around `tree-sitter generate` that skips parser generation if `grammar.js` hasn't changed since last run.
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+**`bin/generate-corpus`**
+
+Unlike most other Tree-sitter projects, we breakout test cases into separate files (see`test/cases`). This is mostly done so editors have an easier time syntax highlighting our test cases but also I find individual files easier to navigate than the `corpus.txt` files used by Tree-sitter.
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+We use `bin/generate-corpus` to generate the `test/corpus/case1.txt` from individual `test/cases` files so we can still use `tree-sitter test`.
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+**`bin/test-corpus`**
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+Run `bin/generate-corpus` and `bin/generate-parser` before running `tree-sitter test`.
